7 in 1 (or any other number!) multicookers come in many different forms from a number of different manufacturers, so specifications vary, and no doubt their suitability for use on site EHU, a specific model or two that you have in mind would give us a chance of providing you with an answer!
I've got a Instant Pot 7 in 1 electric pressure cooker at home (IMHO far too big to take to caravan!), that's max power rating is 1200W, so suitable for even a 6A EHU (but only just, and as the only appliance running!)
As a rough guide the following gives the MAX power of ALL running appliances (don't forget, if you have a leisure battery, the charger will take some power, and things like water pumps and lights may be 12v, but still draw from the EHU supply via the 240v-12v converter/charger unit!) for typical EHU supplies:
6A - 1440W (1.44kW) max
10A - 2400W (2.4kW) max
16A - 3840W (3.84kW) max
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets