I help someone to cultivate a plot but they pay rent and all the produce is theirs and the responsibility ultimately. Well I did plant some peas and gave them half my seed spuds and some french beans but it is very definitely their plot. Kind of wish it was mine so I could do some thing beyond keeping weeks in check! Anyway I have no objection to this kind of help being given to old timers and working people so long as the plot is still theirs primarily, sharing produce fine, reward for all the hard work but not renting out. Its a bit like sharing a plot I guess.
Anyway, the lottie plots where I am waiting for a plot was taken over by the parish in the late 90's I believe, certainly not that long ago. It was over run and badly maintained, loads of plots empty. So they did just what you want to do and split every plot in half and renumbered them as individual plots. So current plot holders holding one plot essentially ended up with two, not sure how that worked out for them in terms of rent though. These days there is a rule that plot holders can hold a maximum of two plots (ie one standard plot) due to the wait list except where they have held more than that prior to the new rul being brought in, so some people still hold 4 or more half plots. However, when I went down to check up on my waiting list status I was told I was no 4 (having been no. 3) so I queried it. Apparantly now they are saying that one of the people ahead of me is waiting for a second plot but because of the wait list (30 or more long) no one can have a second plot til the wait list is cleared, which seems a bit tight as the half plots are really not big enough to maintain even a couple in veges or fruit for a year, so it very much become hobby gardening and not that serious. But I think the two plot max rule is fair while there is a wait list, just feel sorry for this person ahead of me as I'd be cross if the rules were changed arbitrarily like that and I was waiting for a second plot.