Hi @Joe Herrmann, I am a bit confused on why you are trying to save 10-16% of the purchase price if you are stating that you are using an FHA loan? Usually to roughly run numbers, take the 3.5% down payment and then another 3.5% for closing costs, so that 7%. I understand that you probably want to have some savings/reserves but I just don't see why 10-16% specifically.
To answer the partnership question, I don't think you would really be able to do that route if you are going FHA because that means it is your primary residence.
As far as the off market deals, this is hard, costs money, and is time consuming. Unless you have to time to put into it I think your best bet is finding an investor friendly agent that works on getting those and they could be your connection for that type of deal.
All this being said, I am not sure what part of NH you are in but like others have mentioned the market is very competitive right now and can be challenging for someone using an FHA loan to get a multifamily under contract. Not impossible though.
If you have any questions that I could help with feel free to shoot me a message. I also have a 3 unit building in Dublin, NH that could possibly work for you.