Dynamic data validation to determine the SUM related output?

Hi guys,

You were a great help with trying to set up a dynamic data validation, where each of the subsequent data validation boxes change based on the selection in the first data validation box (while maintaining 4 parameters within a cell, except for the last one).

I have used the IF-statements to determine the "Week's SUM" in H5.

What I'd like to do next is to determine a formula in the "Week's SUM" cells (H6,H7,H8) based on the choices in data validation boxes "Week #" (G6,G7,G8) with the following rules in place:

1. If I made a choice in G5 to be "1" which caused data validation in cell G6 to update, then in G6 I choose "2", the output in H6 should be just week 2's value of 20 (not the sum of week 1 and 2).

2. However, if I choose "3" in G6 (after I chose "1" in G5, as above) then I'd like the output in H6 to be the SUM of week's 2 AND 3, if that makes sense and so on. (e.g. If I chose "5" in G6, then output in H6 should be the SUM of week's 2 AND 3 AND 4 AND 5).

Same rules apply for H7 and H8. I have a feeling this may involve MATCH function and INDIRECT or SUMIFS but need a bit more guidance how to approach this.

I've attached a file that which will hopefully make more sense.

Any help would be great!

Stas