why one would treat participation in a Telegram group as an indicator of attendance.
It is an indicator of interest in going, otherwise why join it?
There is no other way I know of of estimating how many plan to come.
Good and constructive discussion here. Thinking a bit more about the TG issue. Apparently there are many more like @tmo who are interested to follow what’s going on but not really seriously thinking to attend. That’s fine of course, but it would be helpful to just be open about that from the start so that the organizers get a feel for how many may actually come. And as things develop, just answer the questions that the organizer may pose. Basic courtesy.
As Peter said, many airports and all restaurants need to know (well) in advance if a group is coming, and certainly the size of the group is an issue.
@Peter and @aart I had hoped to make the back up, but juggling two rosters didn’t work out. I would be happy to pay a nominal fee for the better good of the Forum to participate in Telegram on a future fly-in. RGV have worked through all the avionic squawks on my airplane and the KFC200 is now working smoothly.
Peter wrote:
[Telegram group] is an indicator of interest in going, otherwise why join it?
Lurking is a valid activity, and lurkers are an interest group for future fly-ins.
Peter wrote:
There is no other way I know of of estimating how many plan to come.
Good idea on the Google Docs or the like. Would indeed have saved me a bit of work doing an Excel myself and does have the advantages you mention.
I think the main issue found with the telegram group is that if say there are 30 people in it, and you post asking who is still coming, most people are found to be nonresponsive. Some of those may have disabled / not enabled notifications / have forgotten about it, but the end result is the same.
One would normally assume at that point that all those who haven’t responded for say 1 day have dropped out. And this becomes fairly obvious at say t minus 1 week.
An online spreadsheet would not (I assume) enable sending messages to everyone asking them if they are still coming.
I use a google spreadsheet for other stuff; it works well.
Telegram is also good in allowing huge files to be uploaded, so one can upload VFR or IFR charts, for example. You would not want those in a forum thread (only PDFs would work usefully and then take up space on the EuroGA server for ever).
It has been argued that one could just let loads of people join the tg group and periodically ask who is coming and base the “current list” on who actually replies within say 1 day.
One would normally assume at that point that all those who haven’t responded for say 1 day have dropped out. And this becomes fairly obvious at say t minus 1 week.
So the organizer could change the status of a non-responder to ‘not responding, assumed not coming’, and even group the non-responders at the bottom of the sheet so the upper part remains useful for the responders 
It is now 6 years since I was actively and regularly flying but I’m expecting next year to be the year when I am finally back in circulation.
Personally I use the fly-ins as motivation and am always interested to read the threads. (“One day soon I’ll be able to participate”).
I did once join a telegram group but had no idea why I was there or what I was doing!
If at any point I had seen an opportunity to attend as passenger/co-pilot, I would probably have taken it but since I don’t really “know” anyone else on here I appreciate that invitation is unlikely.
You might get someone’s spare seat if you ask 
I think I remember a few years ago, meet-ups were planned in a long thread and the TG group was set up a few days before. I think it worked well.
If you wish, ask 10€ to get to the TG group and the google spreadsheet. This should segregate lurkers (like me ) from real prospects.
Reasons to me the attendance fell :
Ideas to bring people back :
About the COPA fee, 220€ is not much if you feel like you get something in return (no arguing over the handling bill, ground transport organized etc…).
If it makes your wife want to return, it definitely is worth the money (and we’re talking about Cirrus owners there). But someone is definitely working to make things smooth.
I would say the strong and weak point of EuroGA is the diversity of its members. Type clubs have a much more homogenous population.
