Hi Juca, support for filemaker 12 is already discontinued:
If you are a new user, it's highly recommended that you use the latest version, FileMaker 16.
I think I understand what you are trying to do, but it may not be the best way to do it.
You do not need a relationship between Human MENU and Human DATABASE in order to do what you want to do. You may not even need the Human MENU table at all.
For this type of thing, a lot of people use global fields. You may want to watch this great instructional video on "search field scripting" for some ideas.
If I were you, I would delete the Human MENU table. Then, I would create global fields in my "Menu" table for searching like this:
On the menu page, I would allow users to type into those global fields.
I would make a "Search" button that had a script that looks like this:
Set Error Capture [ on ]
Set Variable [ $freezingdate ; global_FreezingDate ]
Set Variable [ $patientid ; global_PatientID ]
Enter Find Mode [ no pause ]
Go To Layout [ Humans ]
Set Field [ Humans::FreezingDate ; $freezingdate ]
Set Field [ Humans::PatientID ; "==" & $patientid ]
If [ Get(LastError) = 401 ]
Go To Layout [ original layout ]
Show Custom Dialog [ "Error" ; "No records that match were found" ]
With that button, I do not need a relationship at all between Menu and Humans, I take the values from Menu, go to Humans, and search for matches. If no matches are found, it returns and shows a message to the user.
This is some basic scripting, and there are other ways to do it. I would highly recommend watching some training videos as they will help you grow quickly!
You can put many global fields into your Menu table, and perform the same searches for all of your other tables. And you would never need to setup a relationship at all to any other table.