How can I redirect SSH users to another SSH login?

Consider using a ForceCommand directive in sshd_config. For example, I use these to force groups of users to a set of servers:

Match Group group1
       ForceCommand ssh -t group1.fqdn

Match Group="*,!local,!group2,!root"
       ForceCommand ssh -t group3.fqdn

You could use:

Match User foo
    ForceCommand ssh -t target-host

You thought to edit the bashrc file. I would take a look at limiting their access to all bash commands other than ssh this way they can . This link has good information.

Another thought is to setup a ssh pass through tunnel without access to a login. This link might be useful as well. This might be easier to configure.