But the writers could at the very least give a reason for the characters to not be there: stuck at the airport, at home for an illness or injury, too distraught to make it to the funeral, etc. Hell at the very least nowadays they could have someone holding a cellphone/laptop/iPad/etc. to imply that the missing characters that would logically be there are at least watching the wedding.
If they wanted to they could also have the abense part of the story, in The Nanny when Fran and Max got married his mother and brother weren't there and in an earlier episode they had it where Max and Nigel had a falling out, in the episode it is revealed that Max's mother didn't show up because she doesn't approve, and the absence of Aunt Fredia was brought up in a later episode and the bases of the conflict of the episode. This shows that even though a character is absent from the wedding or funeral, it can have an in-universe reason that is explained before, during, or after the event.