Tdap shot

Is it bad I feel awkward asking my immediate family to get the tdap vaccine. I feel like I can't tell them what to do or what to get but i also don't want anyone without the vaccine around my son. My mom, dad and mother in law are the only ones seeing the LO because they are flying to come see us but i feel like that's even more reason for them to get the vaccine. They'll be on a plane with so many germs! I hate confrontation and I hate ultimatums and that's exactly what this feels like.. I would hate to be the one to say they can't come see their grand child if they don't get the vaccine.. how do I cope??