Dynamic data validation list to exclude values selected in the previous cell on the same row

[UrosV]

Hi everyone, this seemed like a simple problem but I'm struggling to see a simple solution. Basically I have a 'Project tracker' spreadsheet that contains two people resource columns. One is titled 'Project Lead' and the other 'Project Support'. The validation list for both of these is based on the same list of names. There can only be one lead, but we can have more than one support. However, the lead cannot be also listed as support for the same project. To keep data unique to row, I added a vba code to allow for more than one entry in the support column separated by a commas. All of the entries are based off of the same data validation list. My problem is for each row to restrict the list to names that are not listed in Lead and also exclude those already selected in Support. But this needs to reset when new entry is made in a new row. See below for the simplified example of what I currently have.
[TABLE="width: 468"]
<tbody>[TR]
[TD][TABLE="class: outer_border, width: 500"]
<tbody>[TR]
[TD]PROJECT[/TD]
[TD]LEAD[/TD]
[TD]SUPPORT[/TD]
[/TR]
[TR]
[TD]myproject A[/TD]
[TD]Josh[/TD]
[TD]Adam, Brett[/TD]
[/TR]
[TR]
[TD]myproject B[/TD]
[TD]Adam[/TD]
[TD]Josh, Brett, Jack[/TD]
[/TR]
[TR]
[TD]myproject C[/TD]
[TD]Jack[/TD]
[TD]Adam, Josh[/TD]
[/TR]
[TR]
[TD]myproject D[/TD]
[TD]Brett[/TD]
[TD]Josh[/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]

[TABLE="class: outer_border, width: 200, align: left"]
<tbody>[TR]
[TD]Project Resources List[/TD]
[/TR]
[TR]
[TD]Adam[/TD]
[/TR]
[TR]
[TD]Brett[/TD]
[/TR]
[TR]
[TD]Josh[/TD]
[/TR]
[TR]
[TD]Jack[/TD]
[/TR]
</tbody>[/TABLE]






Almost all solutions I have been able to find, focus on excluding values along a column range. This however requires that the list be 'calculated' from scracth for each row. Any ideas?

Thanks

Uros