You each file a 709.
You each gifted $100,000 (total) to your son and his future wife ($50,000 each) and have a total annual exclusion of $36,000 for 2024 ($18,000 for your son and $18,000 for your future daughter-in-law).
On Schedule A, you will list each one (son and future daughter-in-law) on a separate line ($50,000 each).
