I found a few days worth of both parents meds wrapped up in tissue, hidden!! I organize their pill boxes. How to approach this situation?

If I found meds wrapped in a tissue in a cabinet the first thing I would think is that they need additional assistance in taking their meds. Sorry this happened but I am glad that you discovered it.

I would be concerned if any other pills were not taken and or stashed elsewhere or even thrown in the trash. Could be a red flag, don’t you think?

Are they alone in the house? No aides helping you? Maybe it’s time to have someone with them or if possible they could go into a facility.

Best wishes for you and your family.

This is a sign that they are no longer able to self administer their meds. I, too, carefully filled my dad's pill box each week and he would randomly take pills from the box. He couldn't remember if he'd taken his meds for the day, or maybe he'd take Tuesday's meds on Monday and then on Tuesday figure he'd already taken them, or sometimes drop them and they'd be on the floor so he'd "borrow" a few from a different day. And this was during a time when he managed to be in his own home, cook simple meals, and take care of all of his ADL's except keep track of medications. I tried giving him a reminder each day and that didn't work as once we hung up the phone he would just do the same thing. Unless you can physically remove all the meds (I had hidden all my dad's except the ones in the pill box) and have someone administer them each day all the admonishments and reminders to your parents won't help.

Anyone has a right to refuse medication. I would first ask them if that is their choice, or if they forgot. If they simply forgot, you may want to take steps to make sure their medication is taken. I would notify their physician if they have decided not to take it. You should be informing your parents on what the reasons for the medication and what could happen if they do not take it. This information can be given by their physicians.

How advanced is the dementia? Could they have devised to stop taking meds or is this more a losing/hiding/misplacing things? Are there other things missing? My dad takes what my brother terms a “stupefying” number of meds, many of which we’d like to see discontinued as they’re from an army of specialists that admit they have nothing to offer anymore but sure keep him coming back. My dad won’t stop any of them, though he says he knows many who have stopped the meds and say they feel fine without them.
See if swallowing pills has become difficult, if there are side effects you aren’t aware of, anything like that. Maybe they are just tired of taking meds and not seeing or feeling any benefits. And maybe the dementia is causing more issues than you’ve seen before

This is a red flag, a sign that they are no longer capable of living alone. If they were in AL, their meds would be distributed to them, no not taking them.

Actually some people with dementia hide the meds because they are afraid of running out and they think that they will die if they don't have them.

Most likely they have no clue where they put them.

It might be time to realize they can not live alone, at least full days.
Forgetting to take medication, not knowing what to do with the medication, being confused as to when and how to take it is the tip of the iceberg.
What else is going on that you are unaware of?
Does the stove get left on?
Does either of them wander? A walk around the block now might not be a problem but what happens when one or the other can not find their way home?
Does either of them drive?
A caregiver, or "companion" might help during the day if they do not need "hands on care" a companion can not give medications but they can remind, put the medication in front of them and watch that it is taken,
Are they safe in the house? Or is it time to consider Assisted Living that may transition into Memory Care?
Is there Adult Day Care in your area that they could go to a few days a week? That would keep them occupied and socializing. Some Memory Care Facilities have Day Care..with the hope that if it came to placing someone you would select that place since the person would know the staff, the facility and the routine.
I would not quiz them about hiding or hoarding the medications as they probably have no recollection that it was done.

By the way you might want to discuss with their doctors what if any of the medications can be discontinued. Given that they both have dementia, a condition that will not get better and is not curable, maybe some of the medications are not necessary any longer. Is a medication for lowering cholesterol doing either any good? if they are taking medication for the dementia to slow the progression, is that doing any good (if it ever did)? I would discontinue any medications that are not actually needed. But do so under the direction of the doctor, some have to be withdrawn slowly.

I don't think it's anything as straightforward as your parents wanting to give up or being tired of taking meds. I think the culprit here is their dementia. People in certain phases of dementia are know to hide their things, stash them away for whatever reason. That the pills weren't just tossed into the trash (which be much easier to get away with from the prying eyes of their adult daughter) but placed in tissue and hidden away in a cupboard leads me to think it's the dementia. They probably don't remember hiding the pills.

This is going to be another hurdle for you to jump. I wish I could tell you how.