Pull data from separate Google Sheet into a Google Forms response sheet and update dynamically

I have a Google Sheets leave sheet for employees where we track the leave days due and days already used. I also have a Google Form which submits responses to linked sheet and runs with Form Publisher for approvals. I'm trying to get available leave days from the Google Sheet to show up in the approval email from form publisher for quick reference rather than having to open the sheet every time someone wants to request leave.
Any ideas ladies and gents?