How do I forward emails from one sender to someone else in Gmail?

I want to forward all emails sent to me from my daughter’s Scout group to another friend because the Scout group are useless and can’t seem to add him to the email list. I use Gmail. I have worked out that I need to set up a filter. When I open the filter form, the Forward To tick box is greyed out and the option is to set up a forwarding address. But when I click on this, there are two problems. I have to enter the email address of my friend and then he has to confirm this. Why? Also this page looks like it is for forwarding all emails not just specific ones. I understand that once the email address is confirmed I can complete the filter and send on only these specific emails. However I am worried that my other private emails will end up going to this friend – I, of course, don’t want this, not even for a short time. So can I do this or just give it up as a bad job and try to remember to forward manually?