How to delicately "upgrade" evening-only guests to full daytime and evening?

We had the same and we just called them and said that we appreciate is late notice but we are now in a position to be able to invite to the whole day, as we have managed to move things around to open up some spaces and we would love for them to attend. That way you have no need to mention drop outs. If you haven't sent an evening invite them you can just send a day one as you still have time for it to look like they were always on the day list

Agree with charlotte on this one hope you manahe to sort it good l7ck x💗

We invited an evening guest to the whole day once we realised there would be space and tbh it did feel awkward but it was definitely worth it to see her there the whole day. I think the fact that you have venue capacity restrictions gives you a good reason for not originally inviting them. Why not say that due to venue restrictions, you were unsure if you’d be able to invite them to the whole day but now you know you can, sorry for the change and you’d understand if they’d still just want to come to the evening do but you hope they can actually make all of it instead. Hopefully they might see it as a compliment/positive that they are the first people you thought of once you knew you had the space.