A question about Constraint Manager

[Tom_Ding]

Hello all,
In the Constraint Manager connected to Allegro Expert 14.2, after I
creating a match group in Net->Routing->Relative Propagation Delay
wooksheet, adding some pin pairs to this new match group, and setting
the scope, delta:tolerance and target, I close the Constraint Manager.
I open the Constraint Manager again. I change the target to another pin
pair in that match group, then I find the attribute "parentGroups" of
the old target disappeared.
What's wrong?

Thanks.
Tom