It does sound as if the actions your daughter has taken—hacking into your accounts without your permission and spending your money on herself rather than in your best interests—could amount
to financial abuse, which is illegal.
If your sibling is acting as your agent under a power of attorney, with her name on your bank accounts, it is surprising that she is allowing these actions. Your first step may be to talk with your sibling about your suspicions, and get some clarification about why she is allowing your daughter to use up the money contrary to your best interests.
You could be more formal about it, by asking for an accounting of how your accounts are being managed—and this would help bring to light the specifics of what your daughter is spending—and where.
If your daughter is financially abusing you by misspending, than you will need to think hard about what action you want to take.
If you want to try to continue living together under the same roof, you will have to make clear what funds she can use. If you feel your sibling is not doing an adequate job overseeing things as your agent in your power of attorney, consider revoking her powers and appointing someone else to do the job.
If you want to start an investigation of your daughter’s spending, with the possibility of pressing charges for financial abuse, consider contacting the local Adult Protective Services agency for advice. In some locales, you can also report financial abuse to local police to investigate, but bear in mind that they are more likely to evict your daughter at once, and that may or may not be in keeping with your wishes.
Finally, if you just want to discuss some possible options with local authorities, consider contacting representatives from the local Area Agency on Agency, who should be willing to discuss the matter confidentially. You can find the local office through the Caring.com website at www.caring.com/local/area-agency-on-aging.