Hey hey,
So I am creating a custom form with a Link field to Event list - the result is of course the event list with the code of each Event and the subject under it.
My question, how can we make appear also the starting date of the event in this Link field ? so I would Like to perhaps either replace the event code ( not necessary ) with the event subject and starting date.
Could it be possible ?
You can write a Python function for this. Look up queries.py for example
https://frappe.io/docs/user/en/guides/app-development/overriding-link-query-by-custom-script
That sounds great but unfortunately that is beyond my basic knowledge haha. I was looking for something more user friendly 
Okay.
Step 1 : If Event is your doctype residing in a Custom app, open it in Edit Doctype, but if it is a default ERPnext/Frappe use Customize Form.
Step 2 : Add event_date or the name field you want to see in the List in the Search Fields field. Remember to seperate it by comma if there are more than one fields
Step 3 : Go to your Custom Doctype and check if you can see the date in the list.