You can have a fk in the same table with another TO on the graph but this gets weird quickly. Just add a join table.
You can build relationship and almost any field in your table, Name/Product/Category/Type etc. It is just up to you.
Duplicate current Table Occurrence (TO) and rename it to something that makes clear to your solution. Then choose the field for which you need the relationship. For example if you want to see all other records that have the same Product, then use field Product to Product and then add a second relationship with your serial number towards the serial number and use not equal to, to omit your own record to appear in your portal
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FeaturesTable::__pkFeatureID = JoinFeatures::_fkParentFeatureID
FeaturesTable|Linkde::__pkFeatureID = JoinFeatures::_fkChildFeatureID
FeaturesTable and FeaturesTable|linked are two occurences of your table. This is then both a self join and a many to many relationship. A many to many self join as it were.
To link one record in FeaturesTable to others, you create a new record in JoinFeatures for each existing feature that you want to link in. Just as a way to get started, you can put a portal to JoinFeatures on your Features layout, enable "allow creation for JoinFeatures in the FeaturesTable to Join relationship and format _fkChildFeatureID with a value list of Feature IDs and names. This isn't your check box, but it's an easy way to test this to see if you've got this set up correctly.
Then, if you want to try using what looks and acts like check boxes for this (but which are really buttons that create or delete records in JoinFeatures, see the "Check boxes with Scrollbars II" example in:
This is a teaching file that illustrates many different techniques for selecting values from a list that go beyond simple value lists and conditional value lists. Each example comes with detailed documentation.
Thanks Phil. I got my head down and did some serious reading. Managed to crack it.