Only the Companies can have ContactPersons well most likely.
"Most likely", "Basically", "In most cases", "95% of the time", are all phrases that do not belong in database development. This is a technical pursuit which requires precise, specific and technical definitions.
First let me point out that you have same named fields in multiple tables that are in a relationship with another: Telefon, email, mobile, GenderIDRef, etc.. That's not correct. Most likely those should exist in one table and that one table should be related and referenced when you need that data. The key is to put the data at the lowest level it is needed.
I think the best way to eat this elephant is to open a blank Access database and paste in all your tables without data, just the structures, and build the Relationship Tool. Open the Relationship Tool and add one table to it--whichever one you deem your "main" table. Then choose a table you think relates to that one table and relate it properly. If they have any of the same fields, you must decide which table actually gets to house that field. Update your tables appropriately. Then, one by one, do that for every table--add it to the tool, making sure it relates to only 1 existing table and reconcilling duplicate fields so they exist in only one table. Do that for every table you have and you should end up with a valid Relationship Tool.