Pipeline Idea Needed

I'm struggling with how to accomplish something in Pipelines. In a previous discussion, it was pointed out that For Each loops run in parallel, which is where this is becoming tricky for me.

Parent Table: Projects
Child Table: Materials
Child Table: Orders
(both are children to projects)

The Materials table has a 'Group' Assigned (A,B,C,D,E,F). So, perhaps 3 items are labeled group A, two labeled B, and so on. The orders table will also have a 'Group' field with the same options.

Upon a checkbox trigger on the parent table I want the following to happen:
1. Search Orders Table. Create an order with the Group Field set to either A, B, C etc. The trick is, I only want the order created with a group that exists (ie, if NO materials are labeled group D, then do not create that order). Also, if that order/group combo already exists, do nothing.
2. Right now, the problem I am having is any way I have thought to run it through a pipelines, it runs so fast and in parallel, that if two Materials items are labeled Group B, then two orders labeled group B are created (versus one being created, then pipelines realizing it has already been created, and moving on).

Any ideas?

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Mike Tamoush
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