Help with correct total

Hello!

Need help to see correct totals. Original data is huge and thus, I have created very small datasets to get the concept right. Also, I don't see an option to attach .pbx file here. Where can I find that option?

I have two tables - Table 1 has Sales(Qty1) on Parts and Table2 has Sales(Qty2) on Models.

Table 1

Table2

Each part of Table1 is related to Models in Table2. So, one part can be related to many models. However, sales on each part remains same as part is not unique to the model. One part goes in several models. Initially, I tried to work with these 2 tables as is. But was unsuccessful. So, I combined the two table as shown below and am achieving accurate result if we select one model at a time. However, it messes up in totals of parts, if we select more than one model or all models. It essentially aggregates all values of each part.

Combined Table - Each part is linked to specific model and is unique row.

So, in below, if I select any part and any model, then I get right information as below.

However, if I select any part & all models, then data for parts are also aggregated. For example, instead of seeing only 195 as Qty1, now we see 390.

What can we do avoid summing up parts? Any speific measure that can be used to help here. Or is there a better way to connect the two tables which was my approach initially, but it was hard to select specific models as I have a huge list of data here and results will show up for all models instead of only the ones linked to part.

Any help will be highly appreciated here.

Thanks!