Combine tables

Hi. I am wondering if someone can help on below.
I have a table of customers and info that I pull to excel from our company’s invoicing system. I would like this table to be read only and I update it every week by pulling a new list and overwriting the table connected to AppSheet.
I however would like to have another customer table for users to add prospective customers with the exact same columns as the read only table.
Is there a way then to combine these tables into one integrated table to which other tables can connect to. For example one integrated table that logs notes for all customers tables (existing and prospective).

Any thoughts, links to articles / posts / sample apps that could help on the topic.

How about if you set the original table as “Adds Only” and then your users can add prospective customers but can’t modify any existing? Then you would need only one table totally.

Just to give you overview of the app. Our current system is not accessible on our phones and our sales reps would like to have access to info on the system in the field even if it not live.

The problem is that new customers are added to our invoicing system frequently (as we start doing business with them) . So this table is not static. This excel table is connect to our system via a data source. So all I need to do is to refresh the source and additional customers that were added to system are added to the sheet.

I am actually not sure what would happen if I added records via appsheet to this sheet and then refreshed later after more customers where added to our system.
I thoughts that new records added to our system would overwrite records added via appsheet, but I have not explored what would happen.
Not sure what your experience is here, but I thought the only way would be to have two tables. One that is added from a data source sheet connected to our system and the other for listing prospective customer that sales reps add via appsheet.
The challenge then would be integrate and consolidate info of both tables in one view.

The idea is that sales rep will capture basic information. Later they can submit credit applications documents via the app when the customer would like to purchase from us. Our order department will capture this information into our system following which delete the customer record in question. The official customer information record will however be added to the app via refreshing the table connect via data source to our system.

So in conclusion I am wanting to use appsheet as a type of “form” as well as a place to look up information that is on our system when in the field.

I would first try to test what happens if you use the same table and adding data from your additional service. When working with database, data structure should always be as simple as possible… same data only once.