I would add a Conditions table with the columns Condition, Step, NextStep.
In that table I'd store all the options for a specific Condition.
For example, Condition "A" can go from Step 1 to either Step 2 or Step 4, but not step 3 and from Step 2 either to Step 4 or back to step 1.
Then The rwos would look like
Condition Step NextStep
A 1 2
A 1 4
A 2 4
A 2 1
Then you'll need to assign the condition that applies to a specific workflow.
As long as you're not trying to built a "decision tree" based on those data, it should work that way. A decision tree would end in an infinitive loop due to 1->2 and 2->1 ....