kitchen benchtops timber cupped split and needs refinishing

Hi, the kitchen benchtops need redoing, see photos. I think it was oz hardwood, red mahogany or blue gum?? and originally finished with Miratone. The boards have split and some have cupped.
Questions: 1. what glue is best to redo the boards that are dowelled and can be clamped with sash clamps? ie benchtop with hotplates inserted
2. What advice for the benchtop with the sink inserted, the boards here have cupped slightly and are uneven and there is a gap. I do not think there are dowels, and no way to put a sash clamp on. Should I plane/sand and what recommendations for filling the gaps ie what kind of product?
3. I will need to sand and resurface the whole lot and whilst the miratone was a nice looking finish, not sure if its practical if careless people put hot items directly onto the benchtops. I prefer a lighter richer look, but an oil type finish might be more serviceable.
Info would be great, I am an amateur gal, so any technical info could you bear that in mind. I only aspired to be an expert noggin cutter while the house was owner built. Cheers Wollemi

I really think they need to come off so they can be re-done and properly clamped while gluing, and then sealed on both sides...but if you aren't keen on that...

Questions: 1. what glue is best to redo the boards that are dowelled and can be clamped with sash clamps? Epoxy (botecote or west) Clamp lightly.
2. What advice for the benchtop with the sink inserted, the boards here have cupped slightly and are uneven and there is a gap. I do not think there are dowels, and no way to put a sash clamp on. Should I plane/sand and what recommendations for filling the gaps ie what kind of product? Epoxy (botecote or west) Clamp lightly, add a little colour (I like a bit of reddish black Prooftint so it looks like a sap run) or sanding dust to match the timber colour.
3. I will need to sand and resurface the whole lot and whilst the miratone was a nice looking finish, not sure if its practical if careless people put hot items directly onto the benchtops. I prefer a lighter richer look, but an oil type finish might be more serviceable. I'm assuming its miratone polyurethane, which is about the most durable finish you can get. Oils will make it darker - and wont give any extra protection against heat, anyway. I'd give it three-four-five coats of epoxy (a few on the underside too, and then sand the top smooth) ... and teach the kitchen plebs to use mats!!!!!

Perhaps not what you want to hear but MS has got it right. It has to come off and all the joints redone. Special attention will need to be given to the end grain around the sink cutout to ensure it is well waterproofed. When it is replaced it should be fixed to the cabinet in a manner that allows for wood movement (like a table top is attached with buttons or brackets that allow for expansion).
I also think part of the problem is that wide boards were used in the first place and that allows more cupping than narrower boards. Moisture and heat are a bad combination and as you can see away from the sink and hotplate the top is in good nick.
Regards
John

Have to agree with the above - can't see a way of refurbishing it without removal.

Sealing the underside is [IMHO] an absolute must.

Regards,
Bob