I agree with @Patrice Penda .
How many GC's have you gotten quotes from?
There's no reason to give up your profits to a GC just because they know construction or they are your brother in law. I mean, they better know construction (that's what you are hiring them for and it's their job)! If you get to a point where you are confident managing contractors then you can become the GC and sub everything out, but until then what you pay a GC for is to understand the construction process and to hire the appropriate and qualified subs - that is the job you pay them to do, not extra. If they bring more to the deal (guarantee debt, found the deal, fund the deal, provide his time/services at cost etc) then you could give them something (5-30%). 50% is more like you put up the money and he does ALL the work, or visa-versa. There are much better ways to incentivize (bonuses for on time completion, penalties for not hitting deadlines).
If your brother in-law is the GC at full cost and he takes 50% of sale proceeds he is taking advantage of your inexperience. Save your equity for investors and yourself, tell your brother in law to find his own deals!
Also make sure you are using a different LLC for each project.