I am trying to find out whether my grandmother, Maria Domenica Arcidio, born 22 June 1910 in Philadelphia to Liberata and Luigi Arcidio was ever officially adopted after her mother's death in 1918 (sometime between 1918-1925). She went to live with Thomas and Julia Lombardi as a minor and ended up taking their name, which is on her later marriage license. I do not know whether Thomas ever legally became her parent or whether she just informally or formally changed her last name. This information is critical to dual citizenship eligibility. Would all of these records be in Philadelphia? Thank you.
If there was any sort of formal arrangement, I would suggest that you start by looking for guardianship records that may be part of probate records in the Orphan's Court in Philadelphia.