I'm thinking 2 parent relationships(below photo) and I want to share information of the child element(people).
Are there any ways?
Create a subset in such case!! If I understood your question correctly, then create a subset for 'Engagement' info and use it in the module. So while creating the subset, check those that are specific. I hope this helps!!
I would suggest to go and create one only parent child relation and make the other by creating attributes in People. Ex: Org (L1)--> Dep (L2) --> People (L3) then create a module(SYS L3 Details) with 'L3' dimension and create a line item to bring in the engagement information. Note: Go with this approach if and only if you don't want to showcase the hierarchy b/w engagement and people in any of your dbs.