Modification in Extension Field !!!!!!!!

Hello Experts,

I have Created a extension field through SDK  in Sales Order . now the created field is showing in sales order screen .

Now my question is --

is it possible to do some modification in created extension field through adaptation mode .????

suppose i have created a extension field ( "list" ) through SDK , now i want to add some more item in" list "Through Adaptation Mode.

so is it possible ...?????????

Thanks & regards

Manoj Kannaujiya