Polaris Coach and Heidelberg Castle

Polaris Coach
Equipment
[1 Blood]
Vehicle. Haven.
During your untap phase, move 1 blood from this vampire to the Polaris Coach or burn the Polaris Coach. While this vampire is acting, he or she may burn one counter from the Polaris Coach to get +1 stealth for the current action. During undirected actions and actions that are not directed at this vampire, he or she cannot block or play reaction cards. A minion may have only one haven and only one vehicle.

Heidelberg Castle, Germany
Master
[2 Pool]
Master: unique location.
Tap to move blood, equipment cards and/or retainers between any two ready vampires you control. (You choose the amount of blood you move and which cards you transfer.) Cannot be used during an action.

During untap phase I control two ready vampires. One of them is equipped with the Polaris Coach. I decide not to burn the Polaris Coach so I move one blood from the vampire to the PC. Now - still during the untap phase - I move the Polaris Coach to the other vampire using Heidelberg Castle. Do I have to move blood from the new "owner" to the Polaris Coach to prevent the PC from being burned? (My guess is 'yes' cos I didn't move blood from this vampire)

Thanx

Thank you for your quick answer.

Correct answer from jhattara and Ankha.

Thank you

I think I get it now (correct me if I'm wrong): it triggers once during the untap phase and the controller chooses when exactly. It is different to the lasting effects like Recalled to the Founder or Anarch Revolt (www.vekn.net/index.php/forum/6-rules-questions/44217-recalled-to-the-founder) which are checking the conditions all the time during the untap phase. Right?