Create Timeline in linechart with 2 measures in one line with a combined x achsis

[petergassert]

Hi,
i am stuck with a creating a linechart.
I git a bankaccount table that tells me the saldo different companies got at the end of month.

Saldo:
Load * inline [
Company,Date,Amount
Company 1,31.01.2021,200
Company 1,28.02.2021,150
Company 2,31.01.2021,100
Company 2,28.02.2021,140];

The amount refelcts the Saldo the company got  on a selected date.

During a month the companies got transactions that will cause a change in the amount on the respective date end of the month. 

Transactions:
Load * inline [
Company,Date,TransactionAmount
Company 1,05.02.2021,10
Company 1,10.02.2021,-20
Company 1,15.02.2021,-30
Company 1,27.02.2021,-10
Company 2,06.02.2021,-20
Company 2,11.02.2021,10
Company 2,16.02.2021,40
Company 2,28.02.2021,10];

The transaction amount reflects all transactions within the month.

Aim is to create a timline in a linechart, always starting with the selected Saldo and all transactions will be cumulated with all values shown before.

Question :
How do i link both tables best?
How do i make sure, that the values of saldo and transactions will be in one measure?
How do i make sure, that further upcomming saldos, as i select one in the past, will be ignored?
How  i cumulate in this case best? Rangesum(Abouve(..) or Sum({<Date={">=Saldodate"}>} Date)

Thanks and best regards,
Peter