Answered: Deploy a new plugin withouth reinstalling agent?

I forgot to say that server version is 2.1.2 and agent client deployed in computers is 2.1.1.1. I could deploy 2.1.2 agent client putting /deploy parameter to 2.1.2 and then I can remove /force parameter, is it correct? It will see that agent client version is lower and then it will install new version, correct?

The question too is when I deploy same agent client version and I want add a new plugin, what is the best way of doing it?

Thanks beforehand.