The road to residency is that your mother had while illegally present as an overstay in the US; a parent of a US citizen has illegal presence "forgiven" and can adjust status while illegally in the US as long as the parent entered with inspection (i.e. cisitor or guest worker or student, etc.) visa.
A sibling cannot adjust status to a permanent resident if not legally present in the US; you must be residing outside the US unless you have a dual intent visa like an H-1B or L-1. If you have overstayed and incurred a ban from entry (for example for 10 years for an overstay exceeding 1 year) or other bar from entry due to deportation, etc., it must be served before a sibling f4 visa will be granted. So, iuf you hope to enter on that basis, you better NOT enter and remain without a proper status.
There are better forums for immigration discussions.
A sibling cannot adjust status to a permanent resident if not legally present in the US; you must be residing outside the US unless you have a dual intent visa like an H-1B or L-1. If you have overstayed and incurred a ban from entry (for example for 10 years for an overstay exceeding 1 year) or other bar from entry due to deportation, etc., it must be served before a sibling f4 visa will be granted. So, iuf you hope to enter on that basis, you better NOT enter and remain without a proper status.
There are better forums for immigration discussions.