A question about setting my wedding date?

I want to set my wedding date to honor my fiance Dad. His Dad and Mom were married April 18th, well his Mom got remarried, would it be wrong to use the date or not? I don't want to hurt any body's feelings, but I want to do something to remember his Dad.
Update: His birthdate is April 14th, it doesn't fall on a saturday next year.
Update 2: His Dad passed away.
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