Thanks @mitchbaylis for insights, few more questions
I was thinking that it is possible to set a state as a list with data type fields (different field types) and later save each input to state’s list based on data field and index and only at the final step save it to database - this is not technically possible or to complicated and easier approach is better?
Could you give a bit more details? i am always confused with bonding data 
As I understand I don’t need to use nested RG (Outer repeating group data source listofnumbers and inner repeating group for reservations? In this a bit lost 