You are right I missed to tell you that are deferred payment to be done days/months in the future

About API cost you mean my internal API (so WU costs) or currency external API (so EUR costs)?

If it is the 2nd it is not an issue because I refresh it every day on db so the cost is allways the same and for all users/payments.

I don’t understand what will be cheaper for you in terms of WU between:

Thank you again for your help!