HELP working out VLOOK formula i need to use across tabs

I think my mind is just frazzled but I need help working out the vlook formula for the attached spreadsheet.
I'm trying to use a vlook up across multiple tabs. (hopefully I've not had a shocker and been trying the wrong approach)

I want the summary tab to search the '3 group tabs' on name, and then to return the number of days for each month. So the summary tab will effectively show the total days for each person (based on the group tabs)

Any help would be much appreciated!

Another .....

In C2

=SUMPRODUCT(SUMIF(INDIRECT("'"&Tabs&"'!A2:A50"),$A2,INDIRECT("'"&Tabs&"'!D2:D50")))

Tabs is named range of sheet names (Group1, Group2, Group3)

Change D2:D50 to E2:E50 to F2:F50 etc in D2, E2 etc

Copy down

Put the tabs names in Sheet1 A1:A3 then "Formulas"==>Define Name==>Name: Tabs Refers to: Sheet1!a1:A3

Oh, I see, I thought you mean somehow the sheet names went directly into the named range. Very clever.

Thanks very much! I think I need to do some reading up to get my head around it!!
I've tried applying the above (1st suggestion) to my master sheet though and it doesn't appear to be working - is it because I have additional columns not outlined in my example file?
I've uploaded a copy of the sheet i'm now trying to use (and just left the sensitive data cells blank)... I'm not sure if i need to try something else or i have made a basic error somewhere...

Any advice is much appreciated!

Originally Posted by JohnTopley

Put the tabs names in Sheet1 A1:A3 then "Formulas"==>Define Name==>Name: Tabs Refers to: Sheet1!a1:A3

I haven't seen this before either - thanks John

i think i've finally got it - thank you everyone (and for your patience with my questions!!)
Now to read up on a few things!!