Platinum Travel Insurance – card usage requirement

[as02]

Hi All!
I have gone through the posts on this forum about the requirement to pay with your Amex to access to Plat travel insurance. Basis what I understand, there are certain benefits of the insurance which require you to have used any Amex card in the name of the Plat cardholder.
However, I would like to clarify – do you need to make ALL bookings with the Amex card? For an upcoming trip, I have booked only the outbound flight through my Amex (Avios + BA Amex). The return flight, local flights, hotels are all booked on other cards.
Will I be able to use the Plat insurance in this situation?
Thanks!