Relating 3 different databases

Here goes nothing...

I have 3 different databases:

Customers

Packing Slips

Control Panel

Customers: has a field called Salesperson in it. This is a simple text field where we enter one of out 4 salespersons initials.

Packing Slips: this is where all of our jobs data is. (i.e. how much inventory shipped out, the price of the job, etc)

Packing slips and Customers are related via the "Customer" field.

Control Panel: this is a new database that involves dates and sorts through the packing slips and show what shipped on a particular date, month, etc. It looks like a calendar (I used the seedcode free calendar to do this) It's all shown through portals from the packing slips db.

Control Panel and Packing Slips are related through a field in control panel that is a global date field = ship date from the packing slips.

Now, i am trying to get some of the portals shown in the Control Panel to not only sort by the ship date, but also by the salesperson.

I currently do not have the Customers db related to the Control Panel db. Because i'm not sure how to do it.

I have to have the Control Panel - Packing Slips relationship in tack, then somehow I need to add Control Panel - Customers.

I just need to show what shipped on a specific date but only show a particular salesperson.

Please let me know if you have any questions or can help me at all with this.

Thanks!