Adding a date column (that has multiple values) from another table

Hello, 

Date table is in top left of image below.   

In the Flu_RMAs table there is a field called  "Last Ship Date".     It is not connected to the date table in any way  (there is another more relevant date field connected to the date table).  

However, I have a situation where I need to use the Last Ship Date field, but I actually need to use with respect to the table next to it called RMA Line Items.   (essentially the Flu_RMAs table contains header data....and the RMA Line items contains line item data).   

There is no direct relationship between those two table, but both are connected to a dimension table called RMA ID.   (an RMA is essentially an order ID number place for returned merchandised).   

I had tried using the LOOKUPVALUE, but because the Last Ship Date field does not contain unique values, it did not work.   

Any ideas how I can get the Last Ship Date field in my RMA Line Items table?