Here are my sample unit files extracted from my real ones. Firstly, here is an example of Service A:
[Unit]
Description=Service A
After=network.target
[Service]
Type=notify
NotifyAccess=all
...
[Install]
WantedBy=multi-user.target
Here is an example of Service B:
[Unit]
Description=Service B
After=servicea
BindsTo=servicea
[Service]
...
[Install]
WantedBy=multi-user.target
