How to assign several Parent companies?

Using my Dolibarr
1

Hi
In Dolinarr 10.0.1 the card of a third party has the field “Parent company”. In this field you can select one of the other companies stored in the system as the parant company. That’s fine. But in a lot of cases a company has more than one parent companies.
How to enter more than one parent company in the field “Parent company”?
Regards
Harald