Not a tax consultant but as far as I know...
For you...the shares would be deemed cashed from the date of transfer so you would have to do a CGT return. And, presuming there's a gain, you would pay CGT on anything above €1270.
For your sister...the €3000 limit would only apply to her if she pays taxes in Ireland. She would have to declare the gift to the IRS if paying US taxes but I've no clue what the limits and rules are there.