Empty cells when data is coming in time-shifted

Hi there,
we created a panel where we get data from two measurements an influxdb via two different queries. Afterwards we want to sum up the latest values of the two queries via transformation. Problem is that the data from both measurements are not coming in simultaneously so that we have an empty cell in the table view so that we cannot sum up the values with a transform.
Any ideas on how to sum up the last values of each query?
Best regards