开云体育

Ideally I would like to keep all the attachments but reduce their size. Is a there a way to do this in bulk? Is there even a way of doing it manually while keeping attachments attached to their relevant post?

No to either, you can only delete them.?

Now if you have a legacy group with Files, you could upload the smaller replacement image there and edit the original message, delete the large attachment, and add a link to the smaller image on Files.? If not, you could recreate the message with the smaller attachment and send it in, then delete the original attachment but leave the original message and link to it, but it would look like you sent the message, I guess you could put some text in the replacement message to indicate it's a repost and link to the original message, a bit messy.

Either of these options has to be done one message at a time.

Cheers,
Christos