linked issues task number

[Kamil Askerov]

Hi. Our Projects have JSM(Jira Service Managment) - JS(Jira Software) automations and linked issues. Our customer sometimes in some project say our staff to solve problem faster than other one and tald this problems name on his(her) side. And our staff cant open that issue - because he(she) havent access to that side. (JSM side) For this I open access to our staff to that JSM side. But thinking its not good solving of my problem. 

f. e.

154 JSM linked issue 132 JS 

if the customer say to our staff 154 he(she) avtomaticaly see the number 132. 

I thinking to have one custom field where I wrote this number from that side. But its not solve this problem. Because he(she) only see only 1 number. Have there in Jira calculated field or something like this where from number in JS we automaticaly see number in JSM part? Waiting for some information or solving this problem.

Thank you.

P S why I can only select Jira Software or Jira Service Managment not both when select in begining of asking question?