Paypal credit multiple payments

Description

Hello I’ve got myself a bit confused with paying off two PayPal credit items. I have been paying off an item from Apple for 8 months which is due to finish in February. The remaining balance slowly going down. I have now added an item from John Lewis on the PayPal credit 0% if I pay the amount I spent off over 4 months which I intend to do. I assumed I would continue to pay off the Apple money each month as normal and then a separate payment would be taken for the John Lewis item for the next 4. However it appears that it has all been lumped into the same pot and my debit payment has remained the same. My question is does this mean I have to pay the entire Apple/John Lewis lump sum off within the 4 months in order to qualify for the 0%. I basically want to ensure the money I add to what I’m already paying goes directly to paying off the 4 month deal if that makes sense. Is it possible?