Adding Additional Fields to Donation Forms

I just started using OLX this week and already have a need to capture suffiixes and spouse's first name.  With many Senior and Junior names in our database (many without the suffix), one reliable way to verify duplicates lies in the spouse's first name.  Sure wish I could select whatever fields I need to capture on a donation form to ensure a clean database.  I understand the goal is not to make the form too lengthy, but I can be the judge of that on my end.