Currently SapphireIMS support single product key for specific version of software( example: 1 key for Office Standard 2010) under product use rights though it allows product keys for different versions of software entitled under downgrade rights( example: 1 key for Office Standard 2010, 1 key for Office Standard 2013, etc). We are planning to support in future release and until then workaround is to use base license with upgrade license for compliance calculation. In your case base version will be Office Standard 2019 and individual upgrade licenses for Office Standard 2010/2013 and 2016 tagged to base license. Point to note is, over all license count should be equal to base license.
Another example on the same -
• Let say the product § which has multiple key (K1, K2, K3).
• Create a base license for P with key K1.
• Create an upgrade license with P with key as K2 and map the previous one as base license.
• Repeat the same for K3 as well. Make sure to give same license quantity in all license which is the total license procured.