In modern induction cooktops, it seems that each hob's coil's circuitry measures the coil's response to a pulse to determine whether there is enough inductive material on the cooktop to keep the hob functioning efficiently (and, I imagine, safely). Some cooktops are more critical than others. My previous Kenmore (Electrolux) and present Frigidaire (Electrolux) cooktops are rather tolerant and can deal with most pots and pans that are within, roughly, 60% of the marked diameter. I haven't actually tested what the size limit is on the largest hob. Wolf small hobs have been reported to work with rather tiny pots, so they are another example.

It is worth noting, perhaps, that the apparent inductive reaction to a pot will depend on its base thickness and material, so a cast iron pan might work at a smaller diameter than a thin Revere Ware pot.

One might think that a slab of cast iron or 400 series stainless steel could be used with a pot on top of it, but this would create a very hot slab and a not as hot pot and I wouldn't recommend it.

What I would recommend is testing different size and makes of pots and pans to find examples that allow you to get the most from your unit at the pan size you hope to use.

What is the smallest pot you can use on your large hob? The wolf large hob on my cooktop allows me to use a 4 3/4 “ pan. That is the smallest I have. However, I did purchase a really cute butter melting pan in Sweden last summer that is only 2 1/2” in diameter. It does not work on any of my hobs. I get around this by placing it in a 8“ skillet on a hob and that works great. I am only melting butter/chocolate that uses a very low temp. I can also put two small pans on the large hob at the same temp level. There are discs that you can place on a hob to use non compatible cookware similar to kaseki outlines above. (I think they have handles that lets you lift them away) - you might look into that for placing pans not recognized on your large hob but not sure how well that will work.

The induction discs work fine, however using them takes away some of the most useful things about induction. Namely Instantaneous temperature corrections. Using them is akin to just using electric resistance. If you are ok with that then by all means get yourself a disc. This will allow you to use any pan despite the material it is constructed from, even Pyrex..

Some of these units are very sensitive. I had a Samsung unit that was very picky about the pans it would recognize. The Whirlpool and my now Frigidare are not very picky at all. Every pan I have will work on every hob. Granted I do not have any really small pans. All of ours are at least 4" in diameter. I have noticed that a small pan on a large hob does not seem to work as effectively as it would on a properly sized hob, however kind of interesting that it works. The disc is probably your best/cheapest option.

After you contact the manufacturer and they confirm that the large right front hob is only a single large coil I would think if this is a newly purchased cooktop the only practical solution is to exchange it if possible for one which has a two coil set under the largest hob. Your hobs do not show a minimum size-my Electrolux slide in range shows a second inner suggested minimum size ring which on the three smaller hobs is about 1/2 inch smaller than the maximum BUT the large right front hob minimum ring is almost 2 inches smaller than the max so a medium size pan will work-presumably because there is an inner smaller induction ring. If no exchange possible then use of an induction disc will be your solution but giving up some of the speed to boil and quick response to power adjustments as other commenters above have mentioned.

What brand stove is this?