Stock Position - Balance At Date

I used to have a database that had all stock transactions and contained two streams.

One was just a simple sum of transactions and hence showed the movement in the month.

The other stream was a cumulative stream so added up those those transactions to show a balance as at a specific period.

I can’t work out how the second one was done, any ideas?

We have tried to do this via Snapshot feature of the Sync and use Snapshot date as a stream.

Found it, tick box in stream Balance Brought Forward