Hi Christer --
Hopefully this will help. It sounds like you need to do a Commit so that the data you entered into the portal is then written into your related table. In FMP 10 you can run scripts when a new Layout is loaded, so you should create a script called "Commit" with one step in it:
Commit Records/Requests [No dialog]
Then, when in Layout mode on any layout you regularly go to after entering data into your portal, go to Layouts / Layout Setup... and click the Script Triggers tab at the top. Check the OnLayoutLoad box and a Specify Script dialog will come up. Select your Commit script. Click OK and then OK again to leave Layout Setup...
Thereafter, whenever you go to this layout, the Commit script will run, writing your new data into the record. You can apply this OnLayoutLoad script triggering to any layout.