Multimember LLC (partnership)--how to pay your children

My husband has a multimember LLC with 2 other members (3 total).  They hope to have a few of our/their kids work with them during the summer to help out and earn money.  Since it is a multimember LLC and not a sole proprietorship how do they need to report earnings our kids work for them.  Each member have their own possible child who may work with them---but they are not the children of all members.  

 

How is this income reported to the IRS from both the business/child/parent.

 

Thank you,