Is it possible to manually install a data field from one model edge to a newer model?

It might not be possible, depending on whether your Edge 540 has received a recent firmware update or not. The problem is that recent firmware for currently supported devices (with support for CIQ 5.2, like your Edge 540) require "sideloaded" apps to be built with a recent SDK. If the app is old enough that it doesn't support Edge 540, it probably wasn't built with a recent enough SDK.

(Sideloading is when you copy an app onto your Garmin device manually, without going through the store.)

And even if your Edge 540 is on firmware old enough to accept an old app as a sideload, it's possible that once you update your firmware, the sideloaded app will be removed.

However, it wouldn't hurt to try.

Note: you will not be able to change settings for a sideloaded app in the Connect IQ app or Garmin Express. If the app uses such settings (which you implied in the other thread), then you have 2 options:

- live with the default settings

- copy settings from your Edge 530 (but you will never be able to change them)

Of course if the app supports changing settings from the device itself, that functionality will work fine for a sideload.

Note that this procedure will not work:

- when the source device (where the app is already installed) is one of the newest Edges which use MTP, or any newer Garmin watch which supports music, because in that case, most or all app types will be hidden/inaccessible to the end user

(There are some older MTP watches which don't hide certain app types. Music apps are always hidden though)

- when the destination device is a newer watch/Edge (as mentioned above)

Procedure:

- Install VS Code on your computer: https://code.visualstudio.com/ 

- if you have a Mac, install OpenMTP: https://openmtp.ganeshrvel.com/ 

- connect Edge 530 to your computer with the charging cable

- If you're on Windows, use File Explorer to navigate to your Edge 530 "drive". If you're on Mac, use OpenMTP 

- copy \Garmin\GarminDevice.xml  to your computer

- open the copy of GarminDevice.xml in VS Code

In VS Code:

- Open the command palette (CTRL-SHIFT-P / CMD-SHIFT-P) and select "Format Document"

- Search for the name of the app you want to copy. I will use the "Stryd Zones" data field as an example here. You should see a result like this:

<App>
    <AppName>Stryd Zones</AppName>
    <StoreId>18fb2cf0-1a4b-430d-ad66-988c847421f4</StoreId>
    <AppId>971762a9-6662-4a53-82bd-57fdfc4f33e0</AppId>
    <AppType>data-field</AppType>
    <Version>156</Version>
    <FileName>D8DL3424.PRG</FileName>
</App>

Take note of the filename (in this example, "D8DL3424.PRG")

In File Explorer / OpenMTP:

- copy the app PRG from \GARMIN\APPS (e.g. D8DL3424.PRG) to your computer

- copy the corresponding settings file from \GARMIN\APPS\SETTINGS to your computer. In this example, it would be D8DL3424.SET (same name as app, except with .SET extension instead of .PRG).

- disconnect Edge 530 and connect Edge 540 to your computer

- Copy the PRG file to \GARMIN\APPS

- Copy the SET file to \GARMIN\APPS\SETTINGS