POA; If married and you want spouse to have first agent, but they get sick or unable can you list a contingent agent?

Yes, you can, and it can be anyone you choose, and it is positively a good idea to have this back-up in place.

It's wise to have backup, or contingent, agents. Others on this thread gave you great advice. One more tidbit: decide upon people you feel you can rely on to fulfill your business properly, get their permission to include them, then get them a copy, or ensure they know how to get a copy, of the POA should their service be required.

Be sure to ask your lawyer about the POA and successive POAs. My parents had each other as primary POA, with a list of children in succession. Unfortunately, my dad did not want to relinquish his POA on my mom, but was making choices for her that were in HIS best interests (and not so good for her). It was tricky to move on to the next successor. Only when he was finally declared incompetent could we get a letter from his doctor stating that he could no longer serve as mom's POA. Until then, there was nothing we could do to help Mom.

There are a few different options: my mother's POA named two of us "jointly and severally" (which basically means either/or) but if there is any possibility of dissent then naming one person with successors is a better option. There are also POAs that take effect immediately vs those that need to be "sprung", with the first kind I was able to use my authority to help my mom with her banking and accounts decades before she became incompetent, with the second kind it can sometimes be a problem getting the documentation to activated the POA.

Yes. You can name as many successor POA's as you want.

Yes you certainly can. The first nominated person can renounce in favour of the next named, or if they are no longer competent it can happen automatically. It depends on how the POA is drafted. If you think that the situation may turn out to be complicated, it is worth getting a lawyer to draw it up instead of using a form from a newsagent or the net.