Help and advice please

[strictlysnoopy]

  Checking my shared matches for my maternal 2xgreat grandparents, I have 12 Matches.  11 of these  share the common ancestor of my maternal 2xgreatgrandparents.  the 12th match has a  common ancestor as my  paternal 4xgreatgrandparents, Ancestry says he is a 4th-6th cousin, 25cms 1% shared DNA.  I understand that way back there has been a marriage/child to link both as both families lived in the same area.   I need your help/advice on how to research this as I have never encountered this situation before.

    Thanks
    Suzanne