I now have the opposite situation of this post.
Initially
List A - Colors
ID Title Lookup Color Idea ID Status
55 Blue Submission 1 Update Submitted
59 Orange Submission 1 Update Submitted
List B - Color Ideas
ID Title Color Lookup Colors ID:
1 My Idea Blue and Orange
After Workflow
List A - Colors
ID Title Lookup Color Idea ID Status
55 Blue Submission 1 Update Submitted
59 Orange Submission 1 Update Submitted
List B - Color Ideas
ID Title Color Lookup Colors ID:
1 My Idea Blue and Orange 55;59
I would have a SITE workflow each nite that would loop thru List A for any updates and then if an update was found in List A then update List B based the Color Idea ID. If this were a single value update to a text field I would not have an issues, but this is an update to a multi-value ID field.