The parrent birth tie is 0 and the child tie is 1...
So just have
*.robage 0 =
.deltie inc
somewhere...
You can't delete the birth tie. but you can replace it with a normal tie and then delete the normal tie
so it would look like this
cond
*.robage 0 =
start
.tie inc
stop
cond
*.robage 1 =
start
.deltie inc
stop
