Link two SharePoint lists and edit at the same time where one list can have multiple items per one item on the source list?

I have two sharepoint lists. The first, LIST1, is a location listing with a unique plant code to each. The second list, LIST2, is a list of contacts with a column that ties back to that plant code. This list can have multiple contacts per plant. There is a separate item for each contact.

I want to be able to link these two lists together and edit them both at once. In the parent list, LIST1, I have a multi tab form and one tab is for the contacts. I want to enter a repeating table in which the user entering the data can add multiple contacts for that site which will add a new item to LIST2 for each contact they add. Then when they go in and edit it will pull all contacts that have the same plant code as the location they are editing.

Anyone have any ideas on how to do this?