I reckon something must have changed recently in that case... The ecurie or so-called coupling system in France applies to owners holding at least a 25% share and trainers with multiple representation (...or at least it did), on the pari-mutual (win part only, the place part is settled on named horse). It was introduced in France to protect punters from controversial results.
France-Galop voted to scrap the rule several years ago in a bid to boost turnover. However, the French Government insisted that the organisers of trotting must also agree... Not sure what stage it has reached now.
Last time I attended (in 2009) the system was in place. I didn’t notice that the PMU prices were coupled this time though.
See below:
In France horses from the same stable or ownership are coupled for betting purposes. In a race, if horses 2 and 5 are in the same ownership they are said to be ‘écurie’. This is shown in the race card by both horses having E1 in the column detailing their names. Should there be another pair of horses in the race both owned by a single, different owner they will be designated as E2. For win bets only, if you back one of those écurie horses you are backing them both.