Best Practice for handling related entities in Application Service / (Microservice)

I have gone through few posts like THIS and THIS, etc. but I couldn't clarify a confusion with respect to design that's in my mind. What would be the best practice to add CRUD for related entities when working with micro services? (my question is generally related to microservices, but currently I'm using aspboilerplate, to be specific)

For instance, I have an entity Product having around seven to ten properties in it. And then we may have another entity ProductContract. Each product can have multiple contracts added/updated.

Question: is it a good idea to create a separate Application Service for ProductContract entity? as it is going to have it's own input/output Dtos and logic, etc.

OR

It is better to create a ProductContractManager and keep its logic there. Then inject this manager into Product Application Service? This way, Product Application Service would have methods like 'AddProductContract', 'UpdateProductContract', etc.