You need to revisit the entire plumbing package. Your second photo shows what appears to be a power beyond sleeve, so the line from that fitting probably leads to the three point lift system. Yes/no? If so, remove that tee (save it for later) and connect the pressure line to your new valve (the one you now have connected to a tee on the pressure side of the original valve) to that now vacant fitting. You will need a power beyond sleeve to fit your new valve (as shown in the attachment from Leejohn) and a hose from that goes to the line leading to three point. The line from the fitting you're now using as a return line from the new valve will connect to tractor sump. This is where your tee comes in. I'm guessing (because I can't see where it goes) the other fitting in your second photo is the sump return. If so, that fitting is where the tee needs to go and the existing return hose from the new valve will go there. I'm no good at adding and drawing diagrams so all I can do is explain things in English.
Here's the theory. Oil flow from the pump goes the inlet of the existing valve, flows through that and out the existing power beyond sleeve. From there it goes to the inlet of the new valve, flows through that and out the (not yet acquired and installed) power beyond sleeve and into the three point lift system. The sump return from both valves can be connected together anywhere and sent back into the tractor sump.
You may need to read through that a few times to get a handle on it, and you may need some different fittings and/or hoses to make it all work out.
