Parents in law visa rejected

[vahb]

I work in US on H1B visa. My parents in law's visa was rejected today. Questions asked were:
What is your yearly income?
What does your daughter do in US?
How many children do you have?
Do you have any friends in US?

Please help on the questions below:

1) In the DS forms my parents in law had mentioned that they will be self sponsoring their trip. When they reapply for visa is it fine if they mention that my son in law will sponsor the trip?
2) After how many days can they reapply for visa?

I would really appreciate any inputs.

[peace999]

Technically they can apply after 3 business days.
But strategically it may not be wise to apply early.

You have posted the interview questions ; it would have helped if you had posted the answers as well.