To clarify something else I saw today: The Preliminary Business Meeting can amend proposals that come before it, and proposed amendments need not be merely technical. They can, as in the case of the proposed amendment to Lisa's Publications amendment be opposed to the maker's intent. There is also no such thing as a "friendly" amendment. Prior to a motion coming before the meeting, the maker can modify it. After it reaches the floor, it doesn't belong to the maker anymore. (We sometimes still call something, "Ms. H's proposal" for convenience, but she doesn't own it.) The meeting has to agree to any changes. Such changes need not be done in full-blown amendment form. Small changes or easily-understood technical changes commonly can be handled by unanimous consent, particularly if it's blindingly obvious that nobody objects and everyone understands that the change is to make a motion clearer. But in any event, once the motion is on the floor, the fact that the maker dislikes any proposed changes to it makes as much difference as any other member's opposition.
I hammer away on this point because so-called "friendly amendments" are a part of "sandlot parliamentary procedure" that I wish would go off and die. They may be well-intentioned, but they send the completely wrong message that somehow the maker of a motion has special rights to control the content of his or her motion. The maker of a motion has exactly one right: priority in recognition. That is, the maker of a motion is entitled to be the first person to speak in favor of the motion. However, once s/he has used that right, s/he does not have any special right of recognition thereafter. I will admit that, debate time permitting, I have suggested that the makers of motions "close" their argument, giving them a second shot at the debate, but I only do that when there is enough time for it and when nobody else is asking for the floor to debate the motion.
Incidentally, while debate at the Preliminary Business Meeting is not intended to be on the merits of a main motion, when anyone is proposing a substitute or an amendment that reverses the intent of a proposal, by its very nature, the debate on the subject is going to have to go into the merits of the original proposal, but only because when you speak against the amendments to the main proposal, you are generally speaking for the original proposal, and you have to make a case for it. What you can't do is go off on tangents into areas not touched by the proposed change. For instance, Lisa's Publications amendment says that Worldcons need not provide paper publications in a membership, but must provide paper publications upon request and at a reasonable cost. The foreshadowed amendment strikes out the requirement to provide paper publications. Debate on whether or not paper should be required upon request is germane. Debate on what sort of formats of electronic distribution would be acceptable, or whether it's a good idea at all to give Worldcons the freedom proposed by the original proposal, is not germane and will be called out of order.
Yeah, I know, it's complicated. But since we don't have a Strong Man of Fandom who makes all of the decisions for you, we have to have a method of debating changes that gives everyone a chance (within reason) and plays fair. Making laws and sausage, however, is not always pretty.