Hi There! I'm not sure I fully understand the question so I'll give a small overview and hopefully the answer will be in there. 
When it comes to system phones (such as MLX or BIS), you cannot daisy-chain them together. 1 telephone for each port on whichever module is installed in the control unit. So, for example, if the house will have 5 extensions, you will need 5 telephones, 5 cables that run directly to the control unit and 5 available ports. Each MLX style telephone requires 2 pairs of wires to operate. BIS (Classic Merlin type) require 4 pairs. If you have only (1) 4-conductor cable connecting every wall jack in the house with the Bell interface, you will only be able to use 1 MLX set. Some more information about the Legend:
Programming the Legend can be very tricky. If you are not familiar with the menus, Calling Groups and some other aspects, you might find yourself doing this:
this:
and/or this:
before very long.
If you have Caller ID at your house and want to make use of it, you will need to be sure that the processor is an R7 and that the module that the telephone line(s) is(are) plugged into supports Caller ID. Call Waiting ID is not available on the Legend, Magix or Partner ACS as very few businesses subscribe to that service. If the system has a 016 T/R module installed to support regular analog telephones, the Legend will not pass Caller ID data to those devices. Only MLX telephones have the ability to display Caller ID.