How do I help my brother-in-law look after my father-in-law in a different state?

CM Yes you can get brain mets from prostate cancer but it is not very common.
Bone is the most common site but it spreads through the lymphatic system so can pop up anywhere.

Not to be cruel, but I agree with Veronica that FIL's condition will worsen except that I'd add no one is likely to be dealing with anything for very much longer. Your BIL should seek help from his father's doctors and extended health care team, asking for support for himself (for which he doesn't need FIL's consent).

[Veronica, do you get brain metastases with prostate cancer? I know you can from breast, not sure about that further possibility in FIL here's case]

You need to find a hospice facility. Medicare should pay for it. Home hospice someone has to be there when aide or nurse isn't there. BIL needs to talk to cancer doctor and explain he can't take care of father.

Elder caregiving is a stressful job in and of itself. I suggest you look for options of moving him to an AL or NH.

Sounds as though FIL is stubborn and uncooperative and will probably refuse to allow anyone to make decisions for him. So if he says "NO" then that is the answer.
However prostate cancer typically spreads to the bones so it won't be long before you are dealing with fractures that will need hospitalization. When that happens if he won't agree to some form of extended care BIL can simply refuse to take FIL home. Dementia is not usually a feature of end stage prostate cancer unless it was pre existing so it will be difficult to have him declared incompetent.
I think the best thing to help would be to make a physical visit if possible so you can make a personal assessment.

Deb, I think vstefans has an excellent suggestion. It sounds like you are a business person, and that's what your BIL needs. For my sister (sudden onset dementia secondary to Parkinson's), I went from Detroit to Maryland for 4 days, collected the papers (LTC insurance policy, info to apply for retirement SS and Medicare, will, POA, retirement account info) and networked to find a good in-home care agency, a good local lawyer, got her and her SO to visit adult day care, etc., located a better neurologist and got them to schedule a consult, visited a memory-care facility, etc. Made copies of all, then went home and finished the "paper" work by phone and online. Neither my sister or her SO wanted day care or in-home care at the time (she's well cared for and happy), but sadly the time is approaching -- it sounds like it has arrived for your FIL -- and we'll be ready.

Do call your BIL, he may need to talk to someone! My BIL called me this week to vent and get some info 40 minutes. We only live 45 minutes away, and used to be close.. but life interferes ( and his wife) LOL I think it did us both good.

Deb if you can ever go out there in person it might all be a lot clearer. It is hard to run TOWARDS a disaster, like a firefighter, but you probably should. If you can't then BIL might could benefit terrifically from someone else to make a few phone calls and find in-home help resources, places to get an eldercare and/or hospice eval, etc. Prostate cancer can be pretty indolent, but poop all over a house and injurious falls suggest dementia or brain or spinal cord mets or both...long distance caregiving and troubleshooting can suck and be a poor substitute for being there more, but it can work and almost anything can be of help.

Just found out from my hubby. Yes the cancer has metastasized but he doesn't know to where. He said I could try talking to BIL, but he is so drained and frustrated right now it is hard to get info from him. FIL up until about 3 months ago was still driving and taking himself to Drs appointments and only telling BIL the bare minimum.

Hubby and I are about to climb on a plane for a business trip for a week and I dread to think what we will get home to.

Does your brother take FIL to doctor appointments? Does he know the status of the cancer?

We don't. FIL won't give us any details about his condition unless he thinks it'll get him a sympathy vote (I don't mean to be cruel or harsh, but it's his MO).

Debbie, do you know if the cancer has metastasized to other organs?

I think one of the biggest issues for my husband and I is the fact that we aren't 100% sure of any of his medical prognosis and FIL is not forthcoming. Most recently FIL had a pretty hard fall and ended up with a head lac and bruising. The main problem seems to be that we are so far removed that we can't get straight answers. Frustration levels are very high right now. We all know he needs 24/7 care, but FIL won't admit it. With out power of attorney are we able to get medical records and/or talk to his Dr's in NH?

I know this is all far beyond what my BIL can cope with as a single guy and I can see (hear it in his voice) how draining all this is on him. I'm willing to step up and be the total B in this situation to stop the whole family trying to be nice to FIL.

I know no one ever knows for sure but is there a doctors estimate of a time line regarding the end of fils life? As you know stage four cancer means spreading of the disease throughout ones body usually so I imagine things will go from bad to horrific - especially if bil continues to try to care for fil at home by himself. Your fil might not like the idea of a nursing home or a hospice facility but it's unrealistic to think home care will continue to be possible without 24/7 care from someone with some medical training. Your fil may not be able to understand this but certainly you, your husband and your bil can see this. Some tough decisions need to be made both to help your bil but ultimately will provide your fil with a higher level of care and soon - if not needed already, care and comfort I.e. pain management. Try to get a prognosis for end of life timeline and make the hard but appropiate decision for a hospice facility, a nursing home or round the clock caregivers. this situation is beyond what any one person should be expected to do.

Perhaps pool the resources available from extended family and help pay for cleaning person for BIL until he can situate FIL.

Debbie, do you have any idea how very stressful and demanding it will be on you and your husband, particularly given his Stage IV cancer? As to that, I'm wondering if he's even physically capable of making a move from NH to TX?

Do you know what his life expectancy is? Stage IV is an advanced state of cancer.

It might be that hospice might be a better place for FIL. I wouldn't suggest this lightly, but it sounds as if he does need a high level of care, and if his cancer can't be controlled....well, there's not going to be any improvement; it'll only get worse, not only for him but for his family.