Here’s one suggestion, if using voice services and the Sonos Skill in the Amazon Alexa App, then to stop speakers grouping automatically, remove them from the speakers section in any Alexa ‘enabled’ groups. See this link: 

https://support.sonos.com/en-us/article/alexa-smart-home-device-groups-and-sonos

H!
 

I have no integrations setup, but the IKEA one.

I don’t use the IKEA remotes, so maybe another user here might perhaps chime in to assist you.

One place the Ikea integration may mess with groups is when you have Ikea automations which involve playing or stopping music on speakers.

I had a bit of a head scratcher when grouped speakers would change overnight. I had modified the speakers to use in an Ikea morning routine and that turned out to be the cause. When it ran it against the selected speakers the Sonos grouping containing one of them would change.

The group change only occurred when the Ikea automation ran with my Tradfri hub. Behaviour may be different with the newer hub, especially if Ikea have enabled matter and are updating things regularly rather than just when the automation runs.

Apart from that my Ikea smarthome 1 app is just a basic remote to whatever groups are setup and music queued in the Sonos app. It gives the ability to play/pause/next/previous and change volume. It also allows the Ikea hardware volume controls to be linked to sonos devices and similar basic control. Mine has no ability to change groups or select music as a user.