may be use some commission?
and alternative blokchain for messages, requests?
That doesn't solve anything. A "request for payment" transaction is still a transaction, and would, by default, eventually find its way into the sidechain that you want to implement for it. Automating a transaction is relatively easy -- malicious entities could easily send out millions of those "request for payment" transactions within the first hour of implementing the sidechain. On the other hand, if you force a potential "requester" to pay a transaction fee in order to use the service, then it becomes useless because malicious parties can abuse it by submitting multiple fraudulent purchases to merchants that use an automated implementation of it.
There's really no need for it anyway. Copy-pasting takes less than 2 seconds.