Have a Minimum Profit Margin.
It is not unusual for partnerships and LLC's to be set up so that partners/members share expenses and revenues in different proportions. I think I see your point about fairness, though. Bear with me....example 1 shows the problem I think you're talking about, and example 2 shows a solution (if I'm right about the problem).
Example 1: The Problem -
In an 11 member LLC, one member brings in business that requires $77 of expenses to produce $100 of revenues. Assume members share expenses equally.
Final result: One member makes $43 ($50-$7=$43). 10 members lose $2 each ($5-$7=$2 loss).
Recomendation: Institute a policy that mandates a minimum operating margin. See Example 2.
Example 2: The Solution -
In an 11 member LLC, one member brings in business that requires $55 of expenses to produce $100 of revenues. Assume members share expenses equally.
Final result: One member makes $45 ($50-$5=$45). 10 members make $0 each ($5-$5=$0).
In example 2, all members start making money if expenses are less than 55% of revenues (assuming expenses are carried equally by all members). Steven, your LLC will will no doubt assign revenues and expenses differently, but I think these example make the case for instituting a minimum profit margin policy.