Setting groups for contacts

Application allows only filtering contacts by group.
It is needed to have an option set groups for contacts.

I would agree with this. This App would be ideal for me to send group txts but it doesn't allow me to set up or add to an existing group.

I second that.

It would be great if the SMS app would already recognize the contacts group created on the phone.

It would equally be great if it would allow me to create contact groups
and (of course) send messages to them AND syncing the group to the
phone.

On a second thought could this be a workaround until a group management is available?
Contact groups created on the phone can be addressed LIKE a single user.
Then let the phone handle the resolutions to the group members.
Not perfect, I now, but might be a stopgap solution.

Then which groups does it support? Google Contacts, Yahoo Contacts or any other application for creating and managing groups?