Relations between Clients and Bill-to

What version of Invoice Ninja are you running? ie v4.5 / v5 v5.8.47 What environment are you running? Docker Have you searched existing issues/requests? Don't believe so, have search and not found other Additional context Would be nice to have a little more features on the clients in relations to each other, ex. a dropdown-field named "Owner" where it's possible to select another client and a view on the client details that shows (link to) all that have that client selected (ex. if Person-1 own Company-A and that Own Company-B) also option of "Bill-to:" where it's possible to select another client invoices should be issued to if work is done for one client. I know that the Bill-To feature will take some work, but the relations dropdown and view would be only 1 database field more on the clients and then a bit of logic and html. The use case is ex. if a Holding have 5 companies and your like to have an overview of all clients and not n…