Q:

What ways exist to group messages in chat?

I would like to know if it is possible to group several messages in chat, so they can be replied to together.
Example:

Foo_user: I had a walk in the park today and found a really nice place under some trees.
Foo_user: I wonder if we could have a barbecue there.
  [...]
Bar_user: @Foo_user this is a really good idea.

A more complicated case:

Foo_user: I had a walk in the park today and found a really nice place under some trees.
Alien_user: I had an awful day at the dentist.
Foo_user: I wonder if we could have a barbecue there.
  [...]
Bar_user: @Foo_user this is a really good idea.

It would be nice if Bar_user's reply could highlight both of Foo_user's messages together. Is there a way for Bar_user to do this?
Is there a way for Foo_user to group his/her two messages together to ensure replies like Bar_user's would refer to both parts of his/her proposal?
If this is not possible, are there other means for Foo_user or Bar_user to maintain a visible context to their discussion, short of creating a dedicated chat room?

A:

You can't. You can basically only reply to one message - and the 'underlying' shortcut kinda refers to the message.
SE chat modifications shows the message ID so you can see this in my screenshot. In addition, as far as I recall, there's also a thumbnail of a message that's been responded to, and that would need fixing. You'd need a fair amount of changes to get what you want.

So, as is, there's no more elegant way than the standard, ping-pong conversation and replies are at best, in a one to many relation, rather than a many to one relation. 

