Mixing Namespaces in a Single Journey

Hi everyone, I’m building an abandoned cart flow and hitting an identity namespace limitation.

• Journey starts with a web pageView (Namespace: CICID).
• Waits 15 mins, then sends a WhatsApp message.
• Needs to wait for a WhatsApp button tap (Unitary Event, Namespace: Phone).

A single journey locks to CICID, preventing me from adding the Phone unitary event in the middle. Supplemental Identifiers aren't an option since both are person-based identities.

The Catch:
I need contextual payload data from both events simultaneously to execute the final step: the cart data from the web event, and the wamId and button text directly from the incoming WhatsApp event payload.

My Current Workaround:
I split this into two journeys:

• Journey 1 (CICID): Fires on the web event, sends the WhatsApp message, and uses an Update Profile activity to temporarily park the cart data into custom fields on the user's AEP Profile.
• Journey 2 (Phone): Triggers natively on the WhatsApp reply event. It pulls the wamid and button text from the event context, and reads the cart data from the Profile.

Is this dual-journey / Profile-update setup the standard best practice for this? Or is there a cleaner way to handle this in a single journey without building custom middleware to inject the CICID into the Meta webhook?

Thanks!
Silvio