How do you feel like you belong in a poly relationship ?

For context:

Let’s say there is the primary partner (let’s call them Craig) and then there are two partners (partner 1 will be Ant and partner 2 will be Bee).

Craig and Ant have been together for a couple years. They’re in a M/s dynamic. So Ant does a lot of things for Craig as it is service orientated.

Craig and Bee have only been together for a few months. The dynamic is fresh (with less structure/protocol) and it’s more of a CG/lg type of dynamic.

Bee sometimes feels out of place and not serving a purpose. Craig assures bee that they are serving a purpose but bee isn’t sure how. How can bee voice this without sounding rude ? Bee understands that everything takes time and that communication is key. But sometimes bee feels like they do not belong and isn’t sure what to say to Craig and how can Craig make them feel like they belong. Bee has done a lot of self reflection and still doesn’t have the answers for Craig. Bee is new to poly.