Data model with multiple fact tables and date fields

[#1]

Hello! I've been working with Qlikview just for a few months, I'm definitely not an expert but in this moment I'm the only one in my company with some knowledge.

In short, I'm working on a dashboard built by someone else and we noticed that when using the the date filters (Month or Day) the numbers are not correct. The totals are correct, but the when you breakdown by month or day the numbers are wrong. I understood he reason: for the time filters the developers used the date field of the main fact table (Emails), the point is that this is not the only one. This is linked to Payments and Arrangements, having both their own date fields. I've attached a screenshot with the data model, highlighting the part I'm interested in. The Emails table is linked to Payments through a field and to Arrangements through another field.

My solution was: I need a master calendar linked to the 3 tables. I tried a unique master calendar and different master calendars for each table, but there is another issue: when I link it/them to the tables I end up with synthetic keys because there are 2 fields linking the tables (the date field and the field linking the 3 tables).

Then I guess that the only solution is to modify the data model, my question is: how? Can anyone give me some hints for this? Or maybe is there another solution easier than changing the data model?

Thanks.