set permission rights for composite data model

I have created a master  data model (model1) and published it to a pro workspace. I want to share part of the data model with another user so that he can create his own Power BI report. To do so,  I created a child model (model2) using composite data model. The only difference between model2 and model 1 is model2 does not contain sensitive data from model1. 

I then shared model2 with the user with build rights. So the problem arises,

 

1. I understand from MS documentation that (

https://powerbi.microsoft.com/en-us/blog/update-to-required-permissions-when-using-composite-models-on-a-power-bi-dataset/), my colleague need build rights to both model1 and model2 in order to create his own power bi report. Is that correct?

2. How about other consumers who need read access to the front-end report based on model2? Do they need build rights to data model1 as well?