Sisters pregnant at the same time

Ladies so I’m 22 my sister is 25 I’m having my baby shower fairly early in August due to moving the following week out of state

She’s two months later than me and wants to do her gender reveal the same day as my baby shower during mine also at my parents asked her if she can change it since I already have invitations done already and she’s not budging. What are your guys opinion on this should I say okay and let her do it when we’ve legit bought everything already