yes it can be done

Hi Guna,

How can i do that?

Jor

anybody ?

a other problem is when you invite someone to a group and he or she denied the inivitation you van invite them again and again. is there a wat to solve this?

Jordi, this is how the Group and Event plugins work. When the users get notifications and click Ignore button they ignore invitation but not refuse it.
If you want users to refuse the invitation, this is considered as a custom code modification.
You can apply to other members for the assistance in the custom code modification forum or to find a developer who can help you. You can do it here: http://www.oxwall.org/market/specialists .

Taissa thanks. And about blocking a user role to invite members ?

Jordi, if you are talking about the functionality which allows the site admin to restrict  certain role to invite users to the groups, then this is considered as a custom code modification.
You may post your question in the custom code modification forum .  Or if I took you wrong - please provide me with more details.

Ok thanks Taissa 

Jordi, one more variant  you can restrict the certain role to create a group. And make a custom code modification to hide the group's option "Who can invite-Participants". In these case only the group creator will be able to invite participants.