Murielle,
Which company did your husband test with?
There are numerous sites which accept DNA results from other sites free, have you uploaded his results to any of those sites?
Have any of your children taken a DNA test?
This should help in filtering the paternal side.
What is your husband's 5 highest matches cMs (outwith known family) & have you checked out dates / places / surnames etc. as possibilities with those & shared matches?
I've been able to solve a few dilemmas via shared matches, via dates, surnames, places etc.
It's not the easiest thing in research but it certainly helps to provide answers where there are questions, however, you need to do the leg-work, buy certs. etc. to confirm things & they're not free!
Annie