How to combine two doctype id and generate new ID

In property doctype i have connection field to ‘Lease’ and this property ID is ‘Arada developer-00176’

and when i click on lease from connection plus button i redirect to this page that time i choose ‘Customer’ here that customer ID plus ‘Arada developer-00176’ this id means property id plus 2024 equal to whatever generate id so that ID is a Lease ID
How we can do this
Please help.