Array formula to return multiple values based on various (OR) criteria

Ok, so I can manage an array formula that returns a value based on a criteria. Simple. But I want to add in an additional couple of criteria. Now I'm stuck....

My sheet looks at a manually entered postcode, finds out what region this is in, and returns a list of postcode I have defined as being in that region. (So the postcode WF1 3JY would return a region of Yorkshire, and list postcodes of WF, BD, L, etc)

I also have a list of engineers, with a column for their home postcode.

I want to be able to list all the engineers from my list whose home postcode matches any of the values on the already created list from the postcode and region entered.

So far I have this, which finds me all the engineers for just one postcode area.

=IFERROR(INDEX('Engineer Data & Referencing'!$A$2:$A$312,SMALL(IF('Engineer Data & Referencing'!$D$2:$D$312=$G$2,ROW('Engineer Data & Referencing'!$A$2:$A$312)-1),ROW('Engineer Data & Referencing'!$A1))),"")

So along with the unlined bit above, I want to add in if(or(list = G2, list = G3, list = G4....) etc. The list in G expands down from G2 to about G15, depending on the amount of postcodes that are returned.

I don't think you can use things like AND()/OR() in array formulas, maybe try something like:
=IF(SUM(IF(list=G2:G15,1,0))>0,true,false)
instead

Attached dummy file. I know the format is a bit messy - for now I just want to get it to work before I make it presentable.

Postcode finder.xlsx