I just wanted to thank you for your ruling. While you were consulting the clerk, I had the opportunity to do a bit of my own research, and I believe I found the section you're referencing on page 1096 of House of Commons Procedure and Practice. It's always nice when we can learn a little something about parliamentary procedure in a meeting.
What's unclear to me in the wording is whether members are free to present anything subsequent, or if the committee has to make a decision that it's interested in considering other matters at the meeting. It says:
While it is considering the matter
—that is, the matter in the letter—
—the usual rules of debate apply. As such, there is no obligation on the committee to conclude debate. If it decides to consider the matter, it may do so as and when it wishes. In addition, the committee may consider other matters at that particular meeting as it sees fit.
Is the process for that to just have members propose motions, or does the committee have to make a decision that it's open to considering other matters in the context of that particular meeting?