Can a trustee of a 2015 will, take a loan on a contested estate, but sign it as the 1993 estate when he was not the trustee at that time?

Three siblings were written out of the family estate. One sibling was left inheriting and executor/trustee. The 3 siblings are contesting the will, undue influence, elder abuse both financial and medical. Documents were filed by the attorney against the property stating they want to go back to the original 1993 will. Recently a Deed of Trust and assignment of rents was found filed with the county, signed by the trustee of 2015, but it's signed as trustee of 1993 when he was not trustee, another sibling was. The document also shows the trustee got a loan from a personal friend not a bank.