Probably a little backwards question, but is there a way to manually relate 2 records (that it should appear in related record) via suitescript?

you can always build relations between records(any record). one of the options is through parent-child relation(which can be defined in NS, through custom field of type select, in the child record, referring the parent, w/ "record is parent"-checked). This allows you to also display the child-records, in separate tab, of the parent record. another option, is to actually build a custom record, refer it to your record, using a custom field, then in that custom record, you maintain all the relations and connections, with other records.(of course, all the relations in this custom record, have to be maintained by scripted customization...)