1. Give each speaker a room, and group them.
2. Expect this not to work well, unless you hardwire as many of them as possible. The Move, of course, can not be wired.  Humans are made of water, and water tends to absorb wifi signals. The result might be lots of cutting out of the signal, and it will be hard to test in advance. 
3. Not sure what a ‘Sonos 1’ is. Sonos has never made a product of that name, is this potentially a PLAY:1?
4. For weddings/parties, the most frequent suggestion is to use a regular PA type system, and not try to force Sonos into a use it isn’t intended for. This would also provide the benefit, if needed, of a microphone access point. 

Thanks for your reply. I have seen many sonos systems in restaurants already and thought of that as a good solution. Why would it work in a restaurant but not in the dinner room? Yeah Sonos:1 should be Play:1.

It is not supposed to create a DJ / Party atmosphere but just some nice music in the background. Probably the title was a little confusing. But if there are these many issues with connections I might change to something else :/

Sorry didnt want to choose "best answer" but only give a thumbs up... maybe someone else has a different opinion/idea?

Often, in restaurants, they are wired with Ethernet cables. They’re often high up near the ceiling, too. 

It’s hard to say with any certainty that this will or will not work. There are too many variables, and you just don’t have the option to test it out in advance, unfortunately. And given that you only get married once (at least hopefully), it would end up poorly if it didn’t work properly. 

If you read through these forums, you’ll see a lot of similar advice. 

I agree with @Airgetlam, and have seen it reported here that a person’s wedding was ruined when a Sonos system which tested fine in an empty hall ended up with serious dropouts once the water bags showed up.  

As for Sonos in restaurants… almost weekly there is a post about issues in a restaurant / commercial setting.

I recently attended a small wedding in a remote location and the bride and groom brought a SONOS player for some background music in the dining room. He’s an IT guy.

As I arrived I was warmly greeted, given a COVID test, and then “by the way, the SONOS is not working”. Of course I was able to deal with this in seconds, but there is not always someone like me on site, and this was a very simple issue. If this had been a large venue with lots of players, I may not have been able to salvage the situation before the dinner concluded. The venue’s idea of WiFi was the ISP’s router thrown on the floor under an open cabinet. Eventually I found a note (posted on a bulletin board across the room from the access point) giving the WiFi password. Fortunately, we came prepared (I was consulted in advance) and did not need that access point.

I agree with @Airgetlam, @jgatie, and @Belly M  this is not a great idea. I’m not saying that it couldn’t possibly work, only that the risk of trouble is high, the reaction time window is narrow, and you will probably be distracted by many other details. As mentioned, if you will be depending on wireless connections, testing in an empty room does not guarantee that the system will function when the room is filled with bodies.