Condition - check if customer is in other journey during journey

@michael_soprano  try leveraging Frequency Capping, When you apply ruleset to multiple journeys, you can prevent a customer from entering a journey if they're already enrolled or scheduled to enter another journey within the given timeframe. This enables suppression like "only let the customer participate in one journey at a time" or "don't enter if already in a priority journey.

You can also assign priority scores to journeys.

https://experienceleague.adobe.com/en/docs/journey-optimizer-learn/tutorials/conflict-management/journey-frequency-capping-and-prioritization

https://experienceleague.adobe.com/en/docs/journey-optimizer-learn/tutorials/configuration/business-rules/work-with-rule-sets