We have four paid adult seats in PE from SYD - SIN. We have put in for an upgrade for all. We have an infant travelling with us

We have another award booking in Business on the same flight (adult).

The award flier is no longer travellling. I want to take up that seat for our travelling party (I understand you can request a name change).

In practice assuming the PE upgrade does not come through the plan is for one of the PE adults to take the Business award seat and the infant to take the PE seat.

My question is can I book the award business seat in the infant's name? I am assuming not as he will not have any adults in the cabin with him. Therefore the only other option is to book a second seat for one of the adults already travelling. Is this possible?

I have heard one way to get around it is to make the booking with a middle initial so it differentiates?

Thanks