Measure logic for different hierarchy level

I have two seperate spend tables Table 1)  Channel Spends and Table 2) Additional Spends, i want to calcualte the total spend by month based on the level of categories :

Categories table has all the levels, that i want to add to the drill down table, and it reads from various two tables as per the following strucutre:

Relation between Categories + Spend = Marketing Dashboard Category Level 5

Relation Between Categories + Additional Spend = Marketing Dashboard Category Level 2

Can you guide me with the best Dax formula to solve this problem.

Your kind support is highly appreicated.

Regards,