I want to setup e-invoicing in BUSY for only one of my companies/firms. How can I do that?

To setup e invoice in BUSY for only one of your company or firm 
 you can follow these steps 
 Step1 Open BUSY and go to open company option 
 Step2 select the Company and open with user id and password
 Step3 Go to administration menu and click on configuration
 Step4 Click on Feature Options and click to GST VAT option 
 Step5 Enable Required Einvoice option and configure location and pincode and press ok
 Step6 Click on GSP configuration and set default GSP for Einvoice generation 
 Step7 fill the GSP user id and password on the particular GSP Field 
 Step8 If there were no gsp account created before then open Ewaybill portal then click to Registration option and click to For GSP then verify with OTP from your register mobile number
 Step9 Click to add GSP and select Webtel Electrosoft pvt ltd or Pinnacle finserv advisory pvt ltd and give a prefix with three character or number Then create a password with maximum 15 digits with upper case lower case numeric and special character in it and click to add
 Step10 after the adding the gsp account will be create then select the user ID and copy and paste it in BUSY GSP configurations particular GSP ID and fill the password then validate then press OK and then save 
 Step11 Go to Configuration menu again and click on voucher series configuration then select the voucher type and its series and click to voucher configuration 
 Step12 enable generate einvoice after saving option and save