legal separation ohio

My mother-in-law (deceased) got what was called a "separate maintance" separation from my husbands father in 1949.in ohio..there were 3 children from this marriage..he left and was not heard from again..we have just recently heard from his grandson(from the marrigae in another state) by way of a geneolgy website..turns out he moved to another state and married again and had 4 children..I assume this marriage to this other woman is not legal? and also there is some money in escrow that has been there since he died in 1979...just found out about this also..who's money is it legally? the first set of children or the second set?since both parents are deceased from the first marriage and the "wife" from the second marriage is still living...it list her as his wife on his death certificate.My mother-in-law never recieved any type of divorce papers from him..could he have divored her and she not be notified? by the way she lived in the same town all the years after the separation..so finding her would not have been a problem for him..we knew he had married in another state but did not know about the childern..the children just recently found out about his first family and have'nt a clue about him not being divorced from his first wife...any info on this would be very helpful..Thank you