We would really like to be able to wholesale this as we have a full plate at the moment, but I have never done a seller finance one before and wondered if this was the best way to go and if so, how would I structure it so it was a win for everyone involved?

I’d suggest your best bet is to go to your local roofers supply and ask for references.

I would assume the bathroom creation would account for drain and supply lines already.

A lot of folks here on BP have full-time jobs and they cannot be running back and forth to buy supplies and chase contractors. 

The contract he proposed is to:purchase the house (20k above their purchase) for 75k.I put 10k into it to fix the roof and HVACHe puts what he estimated as 12k or so to rehabHe believes he can sell for 140k easily FSBO - or use flat rate MLS listingA recent comp nearby (only 1) shows a similar sized, but newer home, much less land, sold for 150k The house needs some new drywall, paint, unsure if tile is still OK, kitchen rehab, 2 bathrooms rehabbed, probably carpet in the roomsMy holding time is 90 days to sell apparently in order to qualify people for FHA loansIs this a good place to put limited supply of my money? 

Also, what kind of structure is he putting all these investors in?

You just need to structure your entities to tailor your goals.

Im getting tired of constantly having to supply the same documents that I had already sent to the broker because they can't locate it again.Thanks again!

@Daniel Tisdale Sounds like the combined lots could be worth moving or tearing down the existing structures and building denser and new.

They have good information and good books on LLCs and other business structures.