Having attended enough conventions, at least on the Democratic side, from precinct to state senate to state to national, there was no parliamentary trick.
Not ever having attended a Republican convention I have no knowledge of how they do things, but for the Democratic conventions at the state level, the platform usually is passed late on the last day of the convention. The last day is when we on the Democratic side have the vote for party chair, which can get contentious. After that vote, the convention moves to start going through the party platform. This means resolutions upon endless resolutions that most people never stay for (count me as one of those people).
Most delegates are aware of the important or contentious resolutions. In fact, those are usually brought first because most delegates are still at the convention.
Let's go a step further, most of the time, what the top brass wants, the top brass gets...especially if it avoids embarrassments.
What I'm going to guess is there was no parliamentary trick. What I suspect happened is that most of the delegates had left by the time of the platform adoption leaving the most fervent supporters of certain items to stay and pass their resolutions. There wasn't a parliamentary trick. Munisteri and others were just outmaneuvered. Their side didn't stay to the bitter end, the other side did.
And there was this gem from TPR:
Texas GOP Chairman Steve Munisteri said the two-week delay in releasing the platform had to do with some clerical errors and nothing to do with controversy surrounding the document.Again, I call bulls**t.
If I had to guess, a number of people, i.e., wealthy donors, maybe gay Republicans (god what an oxymoron), some elected officials and candidates who were catching flack over the issue, called and complained to the point where Munisteri had to finally issue a statement.