Legal Question in Real Estate Law in Pennsylvania

I would need to see a copy of the deed to see what exactly your mother signed. Think of ownership of real property as a bundle of sticks. When someone gives the property away, they give their bundle of sticks to the new owner. When they keep a life estate, they keep one stick for themselves and give away 99 of the sticks to the grantees.

If your mother conveyed away the property to herself and kept a life therein with the remainder to the siblings, your mother cannot unilaterally change it. She would need each of the other 3 siblings to agree to re-convey their remainder interest to her or whomever. If they do not agree, then there is nothing that she can do (barring facts like fraud or something which would invalidate the transaction like lack of mental capacity). What I would do is have your mother take a copy of the document to a real estate attorney and get his/her opinion. If the lawyer agrees with my assessment, then see if the other siblings are willing to reconvey their interests and have the lawyer prepare a proper deed for your mother.