I have been one of the many who have been fortunate enough as a player to lead a family tribe in my earlier days. Although there are some simularities between two branches of a family tribe and tight ally, at least in regards to loyalty to one another and understanding, there are several differences.
A tight alliance is a diplomatic agreement brokered by two friendly tribes to co-operate together. It is brought about by trust, friendship and most importantly free will. Both parties in the alliance have the option to back out any time. An alliance also implies that both parties are individual organisations of their own right and allowed, unless it breaches the so called agreement, to do whatever they want. N/A does not neccessarily need to ask the permission of HARRY to go to war with a tribe such as free Game, it is only courteous to do so. Likewise, HARRY does not need to join in with N/A's wars, it only does so because of the good relationship between the two tribes and the hope that HARRY's favour to N/A will pay off when HARRY gets attacked or wants to start it's own war.
This is different to a family tribe. A family tribe is, like a family in real life, a few entities under one banner. When another branch off of the original branch is born, it operates as a unit with the original branch. Whereever and whenever the main tribe or main leader feels it is best to attack, all branches are forced to attack. Likewise, if the family is attacked, the brother tribes are forced to come to the aid of the tribe being attacked. A family is like a tactical unit, under the command of one leader, and the family mechanism itself is used as a tactic to overwhelm and outnumber the enemy.
Think of HARRY as a family friend to N/A rather than a part of a unit. HARRY doesnt have to follow the orders of N/A, and nor does N/A have to follow the orders of HARRY. They help each other out because they choose to do so.
Now we wait..........................................