Apple Pay Moneris Recurring Payments with top ups

Through our app consumers are able to purchase fuel. We are trying to implement a subscription top-up model where the customers get charged the difference of what they have on their wallet and a maximum they defined in a subscription. For example if the user subscribes to have 100$ on their wallet, and they currently have 50$ we would charge them 50$ (when their subscription renews) and add that to their wallet so they can purchase fuel.

We checked out the Moneris Apple Pay SDK here https://developer.moneris.com/Documentation/NA/E-Commerce%20Solutions/Apple%20Pay/SDK and it mentions how to create recurring payments but is it possible to have variable amount subscriptions as described above.

To summarize is it possible to:

1. Create variable amount subscription through Moneris.
2. Get a token from Moneris by providing an apple pay token which allows us to manage the subscription charging on our end.