I would like my sister to be my daughter's legal guardian.

Some people sign a Power of Attorney to give a person such as your sister the legal authority to make certain decisions. A POA isn't going to grant everything you want such as the right for your sister to add your daughter to her insurance. Whether that is possible depends on the insurance company. Not all companies allow for guardianships or foster care.

You need to realize what you are giving up with a full guardianship. Not the same as fully vacating your parental rights but the next closest thing. If you are sure that you want to pursue this action then the good news is you do not need an attorney. You might want one as the steps can be a bit complex but if all parties agree and it seems to be in the child's best interests the court can be helpful.

Her father will have a say in the process as his legal rights might decrease as well. For federal purposes your daughter might still be his / your dependant; federal dependant credit, SS checks, child tax credit. Review IRS publication 501 for more information on that issue. I have an AVVO guide on the dependant subject but might not be enough detail for your situation.

Guardianship usually does not create a child support order but not completely out of the question. The guardianship should be filed in the county where you daughter resides. Many courts have a family services self-help office. That is probably a great place to start.

Instead of using the term "guardianship" I would suggest that you use the term "custody". Guardianship is a probate matter. Custody is a family law matter.

Does Dad have any rights? Depends on what the last court order says.

I would be glad to talk to your sister for $150 for one hour. I need a certified copy of the last court ordered signed by the Judge. That will tell me what his rights are. Even if he won't agree, then it is not the end since your sister has had her for 3 years, your sister has legal standing to ask for custody of the child.

I don't know what the judge will order regarding child support. Normally both parents would have to pay the aunt child support. However, if the parties agree to no child support the court might order only a nominal figure. I can't address that with any certainty since each Judge has a slightly different policy regarding child support.

Best of luck! Happy Holidays!