i get you did this as exercise but from efficiency point it seem like waste of time just to invite around 60 people (have i got it right if 40 accepted means acceptance around 70%), I would understand if you would have few hundred guests that it's with automating bit if you calculate your invested time compared doing it manually (send me group SMS and manually write in sheet who accepted, refused or didn't answer) you are actually losing time

i wish i had such small wedding