For computation of FAFSA EFC, the income and assets of a non-custodial parent (and any spouse of a non-custodial parent) are completely irrelevant. So if the dad is a non-custodial parent, for FAFSA EFC purposes it makes no difference whether or not he gets remarried.
The assets of the custodial parent, and any spouse of the custodial parent, will be factored into the FAFSA EFC calculation unless the custodial parent and stepparent financial situation qualifies for the simplified needs test. In general, if the parent and stepparent have an AGI of less than $50,000 and every family member was eligible to file an IRS 1040A or 1040EZ, or wasn't required to file a Federal income tax return, assets will not be considered when the FAFSA EFC is calculated.
Edited to add: my responses are based on the FAFSA EFC only. If a school calculates its own EFC for distributing institutional need-based aid, typically using the CSS Profile form (or in a few cases the school's own form), the requirements for who must report financials, what must be reported, and how the calculation will be done will be different than the FAFSA methodology. You will need to go to the financial aid web page of any school that the student has an interest in to determine what the financial aid application requirements are for that particular school. The primary purpose of FAFSA is to determine eligibility for federal (and also state) need-based financial aid.