Need advice about possible tenant

[Thomas Stanley]

I own two houses right next to each other. I am having one family move in today that is getting rental assistance for the next year. The house next door just became vacant and she is asking about having her parents move in next door. they are on disability and have sufficient income to get in. 

my question is, has anyone had luck renting out to family members of tenants? I am a little worried about what will happen if there is a conflict regarding rent.

thoughts?