How Would You Structure this Commercial Deal?

[Bridget Ariel]

Just looking for some advice here. My boyfriend runs a business out of a industrial warehouse. It's listed at 2.6m. My grandmother offered to help buy the warehouse and offered 50% in cash (1.4m). My boyfriend's landlordoffered to hold a mortgage for the remaining 50%. The warehouse would go into a family corporation that owns and manages the warehouse investment. My family does not include my boyfriend...my family's rules and not mine....each member of my family of five would be partners in the corp so that when my grandma passes, the investment is distributed equally among the five family members including my unborn child...my boyfriend is the father. When my grandma passes, Both the baby and I each have 20% ownership.Include voting rights based on percent ownership so that after she passes, the majority of my fam vote to replace The baby with my boyfriend. phewww, stay with me!
To me, it sounds unfair that my boyfriend wouldn’t get any ownership If he’s putting the deal together and making the loan happen with the landlord but my family doesn’t see it that way. On the other hand, his business would face shutting down if an outside investor bought the property and either kicked him out or raised the rent like crazy.
My boyfriend just spoke with some commercial lenders and they are all positive he would qualify for the 50% remaining cash so he doesn’t have to go through the landlord. He wouldn’t qualify for the full 2.6m so that’s not an option.
Getting the loan through another lender is ideal for him because the landlord wants to get paid back in five years.

here’s my question.
how would I present this to my family so he rightfully gets ownership because he's be bringing half the cash? How would we structure this so it's fair for everyone? I am not experienced in real estate investments so I'm sorry if I made it confusing!