[wix-users] WiX Upgrade without uninstallation of existing version

[Ven H]

The MajorUpgrade element in WiX seems to be uninstalling the existing
version. But I have a requirement wherein I have to upgrade from 1.0.0 to
2.0.0 without uninstalling 1.0.0. But this doesn't mean, it will have both
1.0.0 and 2.0.0 showing in the Add/Remove Programs. My 1.0.0 version has a
file, a registry entry, a custom windows service and so on. My 2.0.0
essentially, will modify an existing file and add a new file. In our case,
it is possible to make only changes like these and still increment the
major version. But for this, I don't want to uninstall and reinstall the
services and so on. But if it's a fresh install, all the components will
have to be installed. For example, if a customer has 7.9.0 version
installed and wants to upgrade to 8.0.0 (This technically might be a major
upgrade because major version is updated or minor upgrade because there may
be only incremental changes going from 7.9.0 to 8.0.0?), uninstalling 7.9.0
completely may lead to issues like loss of data and so on. Is there a way
to achieve this? If so, can anyone please provide some steps / examples or
provide some links showing this? Note: I am *not* talking about Patch. I am
able to get a patch working. But I am also confused between Minor upgrade
and Small update.

FireGiant's Tutorial
<https://www.firegiant.com/wix/tutorial/upgrades-and-modularization/checking-for-oldies/>
talks
about using <Upgrade> element whereas there are many other articles which
talk about using <MajorUpgrade> element.
Regards,
Venkatesh