Why, especially, do you need to know if your sister has power of attorney for your mother? What difference would it make to whether you're prepared to help with your mother's care or not?
If your mother did create a power of attorney and name your sister to act for her, she (your mother) did not need to confirm it with anyone - although obviously it would be sensible and practical to have confirmed it first of all with your sister. But if there is a POA, for finance, healthcare or both, it must have been your mother's decision alone and nobody could properly have interfered or influenced her. The simplest way to find out if there are formal POAs is to ask your sister; and it is not a rude or an unreasonable question. If your sister ever should need your backup, for example in dealing with hospital teams or social services, it would be better if you were fully informed as to her status. This is nothing to do, either, with wanting to make changes or anything like that - your sister can't amend the POA for your mother or appoint you legally to act for her even if she wanted to. It's just a question of clarity, that's all.
When you say you have been told by "her" that you "have to" help out, who is the her? Your mother or your sister? Either way, though, there is no "have to" about it. You say that you love spending time with your mother. It would also be fair to your sister to give her your support, because caring for somebody full time in your own home is very heavy going; so that makes two good reasons for you to agree to take part. But there's no obligation, this is your choice to make.
Is there a particular problem between you and your sister?
Poppy, I read your profile about your Mom and since Mom is still of clear mind, could you ask her if she has a Power of Attorney? Don't be surprised if she doesn't know what that is, as she is of that generation where the husband would say "don't worry your pretty little head".
One can help a parent with or without a Power of Attorney. The only times POA comes into play is when the parent can no longer make good decisions on their own due to memory loss, etc.
If your mother did create a power of attorney and name your sister to act for her, she (your mother) did not need to confirm it with anyone - although obviously it would be sensible and practical to have confirmed it first of all with your sister. But if there is a POA, for finance, healthcare or both, it must have been your mother's decision alone and nobody could properly have interfered or influenced her. The simplest way to find out if there are formal POAs is to ask your sister; and it is not a rude or an unreasonable question. If your sister ever should need your backup, for example in dealing with hospital teams or social services, it would be better if you were fully informed as to her status. This is nothing to do, either, with wanting to make changes or anything like that - your sister can't amend the POA for your mother or appoint you legally to act for her even if she wanted to. It's just a question of clarity, that's all.
When you say you have been told by "her" that you "have to" help out, who is the her? Your mother or your sister? Either way, though, there is no "have to" about it. You say that you love spending time with your mother. It would also be fair to your sister to give her your support, because caring for somebody full time in your own home is very heavy going; so that makes two good reasons for you to agree to take part. But there's no obligation, this is your choice to make.
Is there a particular problem between you and your sister?
One can help a parent with or without a Power of Attorney. The only times POA comes into play is when the parent can no longer make good decisions on their own due to memory loss, etc.