pump it out?

Hi all, Im going to prepare to change the fluid in the box.
Kind of had a scare as we took the car for a short drive up the road to the four square (grocer) and came back to a red pool of oil on the ground. Dont think it was mine as was at the front wheel Nearside
Checked when got back home and no trace of a leak,albeit a small drip from the cork seal at the back of the autos sump. Checked the fluid level which when checked a month ago was good, but no oil showing.
Ive a little red pool on my oil drip tray from a while ago so might be a gradual leak from the cork seal,well hope so.
My question is and have heard of it being done, can i pump the fluid out of the pipe that flows out from the box
to the oil cooler (in front of the radiator on my s2 V8) with the engine running.
I would need to switch it off promptly when the fluid stopped and top up with new/correct fluid.
But id rather not change fluid 4 or 5 times to empty it all out.
Any opinions?

You can do it out of the cooler pipe, but you need to be careful it doesn't run dry, and if you top up as you are doing it then as the fluid is diverted in two directions inside the box you could just be pumping a majority of the new fluid straight out again.

Personally I'd do the 4 drain/refills with use in between to mix it all up.

I might as well do the drain/refills if i am going to possibly pump out new fluid.
Thanks again Harvey