joseph- which teshuva was printed first??? Siman 84 or 88? THAT is the important question, not where they are filed in the sefer.
notpashut- you are playing with semantics. Unless you can show that it is an obvious mistake in a teshuva or an opinion(like saying purim falls on the 15th of nisssan) no disagreements can ever be called mistakes by the other side. This is evident from a multitude of teshuvos and events throughout Jewish history. Many have disagreed with others on very important matters – even more important matters than an eiruv- and yet the other side was never accused of making a “mistake”.
A consensus tends to emerge afetr a while and then, the “other” psak disappears into history. But, as long as no consensus has emerged, BOTH sides are right and you cannot “Passel” the other side, even if you may think that there is a chilul shabbos involved.
I think it is absolutely weong for a Rov to give a Psak that is NOT for his kehillah and “force” this Psak on other people. The ROV who does nto hold of the eiruv can tell HIS congregants what to do but how can he bascially force his Psak on other people? Wrong, wrong, wrong