Can I open using a 1C multi convention, clearly alerted and described, with 8 or even less points? Many thanks
Have a look at the Blue Book section 7. I think you are out of luck Steve. But if you made it a 2C opening maybe that could work for you. Alan.
At Level 4 it might be possible, depending on what options you include. In any case, it would have to guarantee 8+ HCP.
Blue Book 7B1i.a is very permissive: it allows anything that has four cards in a minor, and also anything that would be legal for a natural 1NT (which requires no void, no 7-card major, and avoiding two-suited distributions other than 54xx). It turns out that the "no void" is redundant here (if you have a void and no 4-card minor, then you mathematically must have either a 7-card major or else be a major two-suiter). So the rule simplifies to "if 1!c and 1!d show non-strong hands, any distribution is allowed unless it could contain a 7-card major (without also containing a 4-card minor), or be a major two-suiter (other than 54xx)".
Note that most multis include 7-card majors as an option, and hands weaker than 8 HCP, neither of which would be allowed as a 1!c opening. So 1!c is probably not the ideal opening bid for this sort of convention.
It would also have to follow RO18 in first and second seat, which does restrict it a bit - you couldn't open 5431 8-counts with 1!c, or 4333 10-counts.
Yes. A one-level opening bid in a suit:
* 1st and 2nd: rule of 18 and 8HCP
* 3rd and 4th: 8HCP