Index/Indirect/Match Help

If you can place some text (an "x" or something in A135 of ResourcePlan to mark the end of the data, then in Timeline!G4 enter:

=SUM(INDEX(ResourcePlan!G$1:G$135,MATCH($A4,ResourcePlan!$A$1:$A$135,0)):INDEX(ResourcePlan!G$1:G$135,MATCH($A4,ResourcePlan!$A$1:$A$135,0)+MATCH(TRUE,INDEX(INDEX(ResourcePlan!$A$1:$A$135,MATCH($A4,ResourcePlan!$A$1:$A$135,0)+1):ResourcePlan!$A$135<>"",0),0)-1))

copied down and across.