I've reveiwed 1026.9 Subsequent disclosure requirements in regards to skip payments and did not see this question addressed. When mailing the skip payment offer to the borrower is there a requirement that all parties to the loan need to receive an offer or can we just mail to the primary borrower?

Deferred (skip) payment requirements are going to be governed by state law.

Also, if this "skip" payment extends the maturity of the loan and the loans are subject to the Flood Regulations you will have to make sure your determinations are current, no map changes have occurred and to send the notice if the property is in a SFHA.