There is a calculation problem in the domino in pairs.
For example;
Plastic Duck(Player A), Mister Hide(Player B) ,Calamity Jane(Player 1) and Flash Gordon(Player 2) are playing in pairs. Calamity Jane (Player 1) ended the round with a “domino”. At this point system calculates the scor of all players but Calamity Jane(Player 1). But it shouldn’t calculate Flash Gordon(Player 2)’s hand. It should calculate just the loser pair.

There is an another mistake in the game in pairs. If the game is blocked, the scor of the team whose points are lower shouldn’t increase. It is a common rule.
Besides these it will probably beter if these rules add the game rules. They are very important rules of Domino.
If five equals 6.6 4.4 3.3 2.2 1.1 comes to one player, stones should deal again
If more than five stones from same combination 6.1 5.1 4.1 3.1 2.1 1.1
comes to one player stones sholud deal again.

For your first question, scores are calculated this way currently:
If A and B are together, against C and D together, and if A finishes the round for example, remaining dominos in B's hand increase score of team CD while team AB don't get any point.

Counting points of B's in team CD isn't standard, well, but I think it brings a nice dilemma: you can try to get rid of your pieces to finish the round and give 0 to your team, or try to keep high dominos so that, in case one of your teammate wins, your points go to your opponents.

For your second suggestion, I think it isn't fair to do so. If the game is blocked, everybody should get points, because it isn't really possible to determine who is responsible for getting into that situation. Ending the round blocked is like a draw, nobody has won or everybody has lost.

For your third suggestion, I don't understans what's the problem ? Having too much doubles, it's just bad luck. But the second hand you propose is both good and bad.

not If A and B are together, against C and D together,
If a and b and c together,
incorrect calculation
and

If b and c and d together,
incorrect calculation
and

If a and c and d together,
incorrect calculation
and

If a and b and d together, incorrect calculation.
if a and b together must be
and
if c and d together must be
Wrong with the quentinc playroom system calculates the.