The How I Met Your Mother star announced late last summer (10) that he and his partner David Burtka were set to become parents, and they welcomed Harper and Gideon via a surrogate mother in October (10).
Harris was busy filming the family comedy in the run-up to the twins' birth, and he pulled on the emotions he was feeling as he shot his scenes as a dad-to-be in the film.
Harris tells Parade.com, ""When we were filming the movie, (David and I) were about five or six months pregnant and we weren't telling anybody. When the script came my way, we had just started that process, so it felt like good timing.
""It was certainly easy to film things like looking at an ultrasound photo and feeling what emotion that brings. It was a nice little secret moment.""