NH TS115A rear hydraulics

[DBMjdk]

Really needing help to add rear remotes!! I practically have no experience with hydraulics apart from plugging in the QA's!! My tractor has 2 rear remotes that are the standard NH that obviously came with the tractor from new. I need to add a 3-spool for grader blade & top arm, and then have one as a spare. Currently I see 4 lines connected to the standard rear bank. After reading up I believe that 1 = return to tank?(this is 3/8 metal line that looks like it drops into the tank!!), 2 = looks like it has a power beyond port attached and runs to either what is the pump or manifold(3/4" rubber hose), 3 = 1/2" rubber hose to FEL, 4 = 1/2" rubber hose to FEL.
Firstly, would someone mind clarifying what hoses are what :confused2: Secondly, where do I tie in a 3 spool valve system(won't be OEM)? Thirdly, the tractor says the hydraulics are rated at 19.5gpm. Surplus Center shows a 14gpm and a 25gpm 3-spool. Which way should I go with that (unless someone knows of a better combo?)
Thanks for any help/advice you can give!

 

[DBMjdk]

Just elaborating more about the lines connected to the existing rear hydraulic bank; the 3/8 steel line does look like it goes into the transmission so I assumed this would be the hydraulic tank, but it doesn't make sense since typically I would have thought a smaller diameter line would be the pressure line?? It is under there a'ways so maybe I have that wrong ~ any thoughts y'all? I'll take the back tire off and see if I can get a better look at it.
The large hose, which does look like it has the PB port coming out of the rear remote, goes back to the pump (or manifold, not sure which is which). should be the return line ~ shouldn't it? If anyone has a TS115 and had some experience with the rear hydraulics let me know, thanks!