I have two rows in Google Sheets :

Row 3 YYYY-MM (Month) number Row 5 YYYY-WW (Week) number

I want to regroup them by quarter, I have put one "ideal solution" and one alternative solution.

Is there any way I can do this in Google sheets?

here's the example

for week numbers use:

=INDEX(TEXT(C3:P3, "yyyy-"&TEXT(WEEKNUM(C3:P3, 1), "00")))