We got an amazing offer to buy land from family. What do we do next?

This may not belong here.

Background: (location is midlands of SC)

About six months ago my sister in law called us to let us know a cousin of ours wanted to sell their 80+ acres of rural land and would give family first choice for 2k an acre. My husband and I did the research on the taxes, land plots(it’s in pieces) and walked the land. Overall we were pretty happy and decided we’d buy 20 acres. My sister in law initially said she wanted 10 acres, but when we finally got her to go out to the property with us(after months of asking her) she said she was getting 21 acres and acted very weird while we were out there. Just bad vibes the entire time.

We planned to build, she wanted the land for her kids in the future(7 acres per. kid). Cool, let’s work on what area she prefers, since her and mother in law had already made comments that she should have first pick because she basically initiated the deal. We’ve given her months to make a decision. She won’t respond, won’t give us any idea of what she is doing. Eventually we just decided we’d let it go. It’s an amazing deal, but in the boonies and not the most desirable area. We’re in a good place financially and mentally, it just didn’t feel worth it. Her and mil have drama with literally every member of their family and we don’t have time for it.

Fast forward a few months from the walk with her, my husband got a call from his dad this past Sunday. The cousin who wants to sell is having health issues and wants the land sold asap. All cash deal. They offered the remaining 60 acres(in laws bought 15) AND two homes on the property, with the request that the cousin be able to live in one of the houses until he dies(he’s 77).

All of this for $120k. We can’t pass it up so we immediately agree. My husband gives his sister 24 hours to make a decision because we are buying regardless, but if she wants half she has to come up with $60k and be ready to go literally this week. Basically they don’t have the cash(she hasn’t all along) and asked my father in law to pull 60k from his 401k for her to borrow! Now she has already gotten free land from part of her mom’s inheritance, no strings, just given to her. My husband got nothing! My fil turned her down, so she texted my husband that she never should have shared the deal and “it’s not the first time I’ve been shitted on”. Wtf. You had MONTHS!

Anyway, we are meeting with the cousin this week to work out details and start the process of meeting with an attorney for the contract process(and whatever else you do for a cash deal). Once we close on the deal, what next? We were offered advice from our uncle who mentioned starting an LLC and putting the land/properties in a living trust. Is there more we need to do? This is a mostly mature wooded property so we have opportunities to sell for lumber.

We never expected to come into anything like this and it’s overwhelming.

We do plan to rent the second house and eventually stay there when we sell our current house and build out there(~5 years). Anything else we should be thinking of or helpful knowledge on large property purchases?

Sorry this was so long.

TLDR: we are getting 60 acres and two houses for $120 cash deal, what do we do next? LLC and living trust was recommended. Anything else?