Select related record of child table in portal
I have four tables which are connected as follows:
A < B > C < D
In the layout of table A i have a portal which is displaying the records of table B. In this portal I have also a field where I can select a record of C and another field where I can select a related record of D. The value of table D is stored in the field of table B. When I change the record in the layout of table D it doesn't affect the stored value in table B. How can it be done that a change of a record in table D will also affect the record in table B?