Thank you for your reply.
It is not exactly that yet.
I believe the answer is "probably" on the relationship where:
Contacts have many Sevice Orders
Sevice Orders have a "specific date of service" (which is related to the contact name )
1- Via Portal
In the portal service orders are sorted by date.
Is it possible to REFER somehow to the portal and GET the last row?
2- Via Calculation
How do I assign to the contact the date is in the service order I've just created?
There is more to it.
I know as soon I do this IF I delete (cancel) a service order the LAST service order will become the prior service order, and if none exists it will be "".
Well it is one of that things the answer is very close. but lost.....