Distribute values and pivot with two tables

[henrik2h]

Hi, first time ever tried PowerPivot and PowerQuery so bare with me. Tried to read up but don't really grasp it.

I have two tables, invoiced costs (Table 2) and forecast of remaining costs (Table 1). The user should enter forecast into Table 1 and estimate over which period this would take place. After that a pivot table should present all historical and remaining costs together where cost items are on the "y-axis" and periods on the "x-axis".

First problem, I got the impression I could use PowerQuery to first transform the data in Table 1 like below so that I can use it in my pivot table. Am I right and how would I go about doing that?

Second, how do I use the result together with Table 2 to make my new pivot table?

Remaining costs (Table 1)
Cost item	Total remaining cost	Start period	End period	Cost/period
Permits	10	1	1	10
Construction	200	2	10	22
Finishing	25	11	12	13
"Transformation" remaining costs
Cost item	Period	Cost
Permits	1	10
Construction	2	22
Construction	3	22
Construction	4	22
Construction	5	22
Construction	6	22
Construction	7	22
Construction	8	22
Construction	9	22
Construction	10	22
Finishing	11	13
Finishing	12	13
Already invoiced costs (Table 2)
Cost item	Period	Cost
Land purchase	1	100
Ground work	2	15