Hello,

I have move the topic to the correct category of the forum...

The user registers for an event, and stay locked to register in other event ...
Is this possible?

Not today possible, but it's an idea i've got for the future. But with options (not blocking for all events by default, but for a selected list of events, or all events, or none, as options for this).
Not planned as a development for this year, and 2016 development roadmap not set yet

Regards,
Cyril