How will co-signing will affect future opportunities? (San Diego)

[Nathaniel Donnelly]

Hello BP!

I have two friends, a brother and sister, that are looking to co-sign on an investment together in San Diego. The brother will be using a VA loan, and living in the house as his primary, and he will leas individual rooms out. The sister is married, but will be in the market to relocate with her family to San Diego in about 1 year's time.

My question is this: How will the sister's act of co-signing affect her family's ability to purchase a home when the time comes?  Aside from the obvious, is there anything else they need to be aware of?

Thanks in advance!