Filtering calculated measure to remove one category

Hi all

I've got a fairly complex scenario that I'm trying to get my head around. I've thought about using a couple of measures to resolve, but they aren't working in the way I expect, so hoping someone can help me either fix the measures, or suggest a better way of dealing with the scenario.

I'm using Salesforce data, and reporting on the value of quotes issued to customers. We have several locations, and I have a locations table linked to my quotes table so that Location can be used as a slicer in visualisations. There are a handful of quotes that involve work by more than one location, and these have the Location set to "Multi". The business would like to be able to attribute a portion of the "Multi" value to each relevant location and roll these up into a measure with the value originally attributed to each location, but still retain the ability to report on "Multi" and non-rolled up values.

My plan is to have the portion assigned to each location stored in a field on the quotes record, then hold these values in a seperate table in Power BI, linked to the original quotes record. I've figured out how to unpivot the tables and store the values so that they look like:

I currently have a measure to work out quote value, that picks up the relationship to my exchange rates table and my calendar table (because I have multiple dates on my quote table):

Value of quotes (000s) =
var ExchangeRate = MAX('Exchange Rates'[Conversion Rate])
return
CALCULATE(DIVIDE(SUM(Quote[Value]),1000,0)/ExchangeRate,
USERELATIONSHIP(Quote[QuoteIssuedDate],'Calendar'[Date]))

My plan was to make a copy of this measure, adding a filter to remove the quotes with location of "Multi", make a measure for my multisite locations table and then a third measure adding the two measures together. But my filtered measure isn't returning the right values for the other locations. This is what I've come up with:

Value of Complete Site Specific Quotes (000s) = 
var ExchangeRate = MAX('Exchange Rates'[Conversion Rate])
return
CALCULATE(DIVIDE(SUM(Quote[Value]),1000,0)/ExchangeRate,
FILTER(Quote,Quote[Location] <> "Multi"),
USERELATIONSHIP(Quote[QuoteIssuedDate],'Calendar'[Date]))

Can anyone tell me what I've done wrong? Or am I going down the complete wrong path for this scenario? Any advice greatly appreciated!

Many thanks

df