Kathy,
Technically, if there is not a quorum then it is not a meeting.
However, as the references below outline, the clear intent of the open meeting statute is to preclude private board meetings. The manual goes on to say that even working sessions (discussions without any decisions being made) must be open to the members.
If one director is trying to circumvent the statute by having the same discussion with multiple directors, ethically, it shouldn't happen. I expect that the individual is simply passionate about the issue and trying to gather support or explain their position in a more relaxed environment. However, it should not be the same conversation with each director outside of a meeting.
As an option, my Association would send info out via email so board members could formulate questions to be asked at the next meeting. There would not be any discussion or answering of questions via email (unless it was an action without meeting). I would often write up a position on an issue and send it this way. Again, no discussion. Only an attempt at not making a meeting longer then it has to be.
It should be noted that these emails were also presented as a report at the meeting which was attached to the minutes.
I offer the following (although it's only a guide and not something that must be followed):
Fairfax County Community Association Guide 2020 edition. Board meeting info starts on page 25 (you can simply click the section in the table of contents)
Fairfax County Community Association Manual (earlier version of previous document. I think it was the first version and believe it gave better explanations.
Hope this helps,
Tim