Adding tenant id in intermediate message throw event?

I am having a "intermediate message throw event " that uses an expression to send a message to start another process instance, like this:

${execution.getProcessEngineServices().getRuntimeService().createMessageCorrelation(“Some id”).tenantId(execution.getTenantId()).processInstanceBusinessKey(“some process Id”).setVariables(execution.getVariables()).correlate()}

I have added the bold part, as we added multi tenancy to Camunda. However, when we use this change, I think it will not backwards compatible, as current process instance does not have this tenant Is set when a message is send, such that Camunda throws an exception that it doesn’t know which process engine to use (the reason we added the tenant id in the first place).

What is the best way to deal with current models that do not have this tenant set such that they still work?
Can I modify current process instances (the expression)? Set a default tenant id? Or is the teantIdProvider used if not tenant is is found? Maybe use some kind of java delegate (also as a general improvement)?

As you noticed, I am a bit confused, please some advice?