I would like to build an app with Zoho Creator, that looks like the "Events" app already provided, but with others capacities. 

I want to reproduce the function of "picking list" for invitation (cf. screenshot).

I've already tried to put the "Lookup" and the "Zoho CRM" field in ZCreator, but it only allows to choose one contact or one account, but not to pick severals. 

Does anyone have a solution to help me please ?