Sum Multiple Rows with an Index/Match

Hello,

I have a data set that has tenants listed down column A. In the columns to the right I have 13 months. December PY through December current year. The columns house the tenants square footage by month. If a tenant..say Apple expires in March and renews I would see that tenant on two lines in the data. December PY through March would have the square footage say 1000 a month. The remainder of the year would be zero. The second line they fall on would have April for 1000 through December for 1000. I am using an index match on another tab where I only have the tenant on one row and need the formula to pull Apple 1000 for December prior year through December current year. The index match finds the first instance so I am missing April through December.

=INDEX(JDESqFtg!$A:$Z,MATCH('RE Tax Cntrb Sched'!$C19,JDESqFtg!$Z:$Z,0),MATCH('RE Tax Cntrb Sched'!J$10,JDESqFtg!$6:$6,0))

Is there a way to tell it to search and find the first match and add it to the second match and so on? Or would the SUMIFS work better?