I understand I can use the uf cable as long as I have a messenger cable but wasn't sure if I can utilize the one on the triplex?
My first impression is that since the messenger wire in the triplex is part of a 396.2(3) factory-assembled aerial cable, it cannot itself be used as the messenger wire for supporting additional wires under (1), (2) or (4). (The reasoning being that you have no way of attaching directly to the messenger wire rather than attaching to the triplex.
Your term "messenger
cable" is not one recognized by the NEC, which only refers to messenger
wire.
Also, FWIW, the messenger wire included in the triplex is factory sized to safely support the weight of the triplex, not additional wiring attached to it.
Article 396 does not address the engineering design of a messenger supported cable system, particularly one which is field assembled.