Incrementally load data between modules via actions

Hi Community, 

I am working on a headcount use case where I plan to load data from source module to target module incrementally. e.g.

First Run - 

Let's say the target module has 0 data initially for a product and market in a specific month.

I update the new value to 100 in the source module for the same product/market/month, which should/will update the target module value to 100.

Second Run - 

In the next run, the source module now has 150 for the same product/market/month, The expectation is that on run the process a second time, the target should show 250 ( Existing 100 + new 150 added).

Can we achieve this without any staging line items? If yes, then how? 

Please help.

Thanks

Dinesh Barua