LB behavior for backend IP connections

lttarvina F5 does support using the same destination IP as long as something else is different with the destination. As long as one of the following is different you can use the same IP for as many of those variations as you can configure.

source IP
destination IP
destination port
protocol

The following is the supporting document and you can search for "About virtual addresses" to find the appropriate section.

https://techdocs.f5.com/en-us/bigip-14-1-0/big-ip-local-traffic-management-basics-14-1-0/about-virtual-servers.html

From the diagram you provided, it looks like you want to use 'layered virtual servers' (i.e. where traffic from one virtual server gets forwarded to another virtual server). You can do this based on the HTTP host header of the client request (assuming that SSL is terminated on the BIG-IP) using an iRule e.g:

when HTTP_REQUEST {
    set HOST [string tolower [HTTP::host]]

    switch $HOST {
        "<FQDN 1>"  { virtual <VS NAME> }
        "<FQDN 2>"  { virtual <VS NAME> }
        "<FQDN 3>"  { virtual <VS NAME> }

        default     { HTTP::respond 200 content "Invalid Hostname" }
    }
}