Using IIF and OR in a Query Criteria

Hi,

I'm quite new to access and teaching myself most of it using the internet so this is probably an easy question.

Basically, I have a Combo Box [Forms]![Sales]![Site] which a user can use to select either an exact location or a market area for multiple locations.

I also have a query for sales with a SellingBranch field on.

I want the query to display sales for only specific selling branches as chosen using the above Combo box. However, I'm struggling to get it to display multiple selling locations for one selection. For example I want to tell it that if [Forms]![Sales]![Site] is "Bolton MA" then the query needs to show results for when the SellingBranch is either "Bolton" or "Chorley".

At present I can get it to work to show just Bolton but don't know how to adjust it to show Bolton and Chorley when "Bolton MA" is selected.

IIf([Forms]![DatesSalesLeague]![Site]="BOLTON MA","BOLTON","MANCHESTER")

Thanks in advance for any help!
Kim

Using IIF and OR in a Query Criteria