Dynamically change the transaction rate using the delegated service

My configuration:

  1. API service that contains a complete bitcoind node.
  2. Client's portfolio: I have no control over that system.
  3. User application: who gets the barcode for payments.

    • So, My API (1) he only has the Address of reception of the Customer's purse (2).

The problem:

Let's say that my client is a hotel, I want the API (1) to set the maximum rate for the transaction if the user (3) You want to get a room today and the minimum rate available if the user establishes a reservation within two weeks from now.

Main question:

Is it possible without any control over my clients (2) wallet?