We have two products. Both can be installed separate but also installed at the same time. Both are send as single MSI file. The issue is now the upgrade. If someone get a new MSI for the first product it must fit at least to the major version of the second product.
Reading the docu :
The UpgradeCode property is a GUID representing a related set of products. The UpgradeCode is used in the Upgrade Table to search for related versions of the product that are already installed.
This sounds that we can use the same upgrade guid for both products and the installer can manage than the detection of the product versions for both.
Is this the correct way?