Disable disconnecting that would damage relations

[Janjko]

Disconnecting 'from' and 'to' members from the 'via' point or way in the same turn restriction should be prevented. Also, 'via' and 'via' from the same relation shouldn't be disconnected (there is not a lot of turn restrictions with more 'via' ways, but it's possible).

This issue is closely related to #1512

[jfirebaugh]

From duplicate:

The "Disconnect" operation should be disabled for vertices that connect two member ways of a multipolygon. Disconnecting such ways produces an invalid multipolygon.

[SHARCRASH]

I work a lot with MP. This breaks horribly the workflow! Instead of disallowing the disconnection, why hasn't there been inserted some sort of simple warning before saving?

Edit:
@jfirebaugh
I had made this suggestion a while back in another post... I've replied to your question on the same post.
#2792 (comment)