Precondition transformer to control order

Related products: FME Form

Imagine a transformer connection similar (or let's be honest, exactly like) the ArcGIS model builder "pre-condition" connection. The reason being is to force with 100% surety that certain features will arrive or pass before being sent/started. Ordering the Readers doesn't help when there are memory intensive operations which slow the first swim lane down and the second swimmer still "wins." A simple, "hey, I know you're fast and all just hold on until you receive all features from 'pre-condition' condition would be a quick fix.
@ryanproulx - A modification to the Feature holder could work too... IE allow the user/author modify what order the features leave when multiple 'swim lanes' merge.

Basically merge the swim lanes in the "new" Custom Feature Holder which will hold until all data arrives, then release all the features in the custom order specified.