Is there a simplified response somewhere with loading performances safely without deleting current edited data?

If by “current edited data” you mean data contained in your USER BANK, yes there is.

If you LOAD a .X7U file it will overwrite the current User Bank.
If you LOAD a .X7L file or translate a compatible file type to a Library, it does not overwrite anything.
If you LOAD a .X7A file it will overwrite all data that you may have created with your MONTAGE (this is truly a backup of everything).

You will first need to get clear on where MONTAGE stores data. What data is in ROM (Read Only Memory) and which data is in RAM (Random Access Memory).

ROM data includes all 2707 Preset Performances, and any Libraries you have installed. These are never, ever, ever, overwritten by any LOAD operation (except for the BACKUP File .X7A... which literally replaces all data that you could have possibly added to the MONTAGE).

You can Save the current data in your User Bank to a User File .X7U
Loading a User File always overwrites the data currently in the User Bank.
User Memory is RAM — It is the work area of the memory.

Knowing that when select a File to Load, if it is a .X7U file, you will receive a warning - that loading the currently selected file will overwrite the all User Bank data. Don’t panic, this is a friendly reminder that you should make sure you have a .X7U file that contains the current set of data. If you already have that file, then just continue and overwrite the User Bank.

It’s the same as when your computer reminds you to SAVE a file before you close a program. Say you open a Document file on your computer.. you read it over, then decide to put it away.. you are asked do you want to save before putting it away. If you already have a file of the letter and you made no additions or changes to it, you just ignore that and close it. It is that type of reminder.

You can, LOAD data into the MONTAGE directly to an available LIBRARY. Say you have a Motif XF file or MOXF file you want to listen to, but you don’t want to overwrite the current USER Bank... by Loading them directly to a LIBRARY you avoid overwriting you’re current User Bank. They go directly to ROM, where you can play them... if you wish to select some of them to add to your current User Bank, you can use the “Library Import” function to add Performances to the current User Bank.

The User Bank is the assembly area where you can gather a set of Performances, Waveforms, Arpeggios, MicroTuning, Curves, etc.,

MONTAGE User Files .X7U can only be loaded to the User Bank. You cannot directly load a .X7U file to a Library.
So what if you want to move individual Performances between files... this is where you can use MONTAGE CONNECT, or the Soundmondo App... They can capture an individual Performance.

There's one more way to not overwrite anything.

Soundmondo has sounds. You can one-by-one sync sounds to your Montage and then [STORE] them directly to the user bank. This will not overwrite anything. Assuming you have space in your user bank - you can keep (one by one) loading Performances others have contributed.

This is an automated way of "loading" X7B files. If you find X7B files - then loading of these through Montage Connect is the same sort of process as Soundmondo. You'd have to (one-by-one) [STORE] each to the user bank.

If you're trying to load "a bunch" of Performances - each of these options is cumbersome since it's one at a time. But does round out the possibilities.