Custom signer labels

I’ve successfully setup a Template with 4 signature merge tags, and have been able to assign recipients to them. For example...

Tenant 1
{{*Sig_es_:signer1:signature}}

Tenant 2
{{*Sig_es_:signer2:signature}}

Owner 1
{{*Sig_es_:signer3:signature}}

Owner 1

{{*Sig_es_:signer4:signature}}

This usually works perfectly, but in a Letting Agent scenario there could be 1 tenant and 2 owners - and therefore the first Owner would end up signing the “Tenant 2” field.

Is there a way round this? Can I use custom labels, such as {{*Sig_es_:owner1:signature}}?