Not at all it's important to you and special. Other people won't micro analyse though.
You could try something like
Dear A and B
We're getting married at -church- on -date- at -time- and would be very happy if you join us there, then to celebrate afterwards at -venue-
insert any other...
Congratulations OP, hope you have a lovely day.
I'm quite old skool, but if I was writing an invitation today I'd be less formal and say something like
You're invited to the marriage of X and X on -date-
at -venue-
Then celebrating afterwards at -wherever- until -time- (if you have a fixed...
