How to bring in previous balance into current module? Or how do I bring in a rolling balance forward

I am creating a balance sheet. I am hoping if anyone can show me the best approach. I have two module. 

Previous balance module and current Balance sheet module.

My previous balance module have no time scale. I want the previous Ending balance in my current module. I attached 2 screen shot to show you what I mean. When I try to add them together, my previous balance module add it to each month. How do I include my previous balance amount without it affect my current month?

Example

 FY18. Ending Balance    = 100

Jan 19 = 20

Feb 19 = 20

Mar 19 = 20

Q1 FY19 = 160

Apr 19 = 20

May19 = 20

June19 = 0

Q2 FY19 = 200