Special deals farm

So i am wondering if im doing the special deals with my friend and we change ch for kill the little bosses on the other channel the special deals of the channel before will be deleted and we will not get any money from those?

example: "im in ch 4 and got 20 forbiden books on the special deals, i go to ch 3 and start a party there and farm 25 forbiden books there." ----- will i get the 45 or only 25?

 

In your scenario, 45.
20 you got from ch4 earlier will be registered into SD market queue, while the 25 you got from ch3 is still accessible via the SD menu.

 

Youl get all money from items you have farmed from all channels.

 

and is there anyway that i can farm special deals alone or i really need a party to do it?

 

Sadly you cant, you always need party member. Also that party member must be within certain range near you to make SD work.