Correct!
Ald-Vendras V3 and V3.1 are compatible with LoKKen and Solstheim Castle by using alternative files which are already included in the download.
Just choose the version which suits to your mod selection and you are fine.
Part out of the readme of Ald-Vendras V3.1 for more information:
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Copy the files into your Morrowind\Data Files\ directory.
Ald Vendras v3.0 comes with 3 .esp files:
Ald Vendras_V3.esp (this is the base .esp for Ald Vendras v3.0).
Ald Vendras_V3Lokken.esp (ONLY for users who want to run Ald Vendras AND The White Wolf of Lokken mod (B_Whitewolf_1_0.esp is required)).
Ald Vendras_V3LokkenSC.esp (only for users who wish to run Ald Vendras AND The white wolf of Lokken AND Solstheim Castle plug-in (for this .esp file,
BOTH the B_Whitewolf_1_0.esp AND the Clean Solstheim_Castle_v1.1.esp are required)).
When you run Morrowind, click on Data Files, then check off your chosen Ald Vendras_V3.esp file and run the game (use only ONE .esp file, never use 2 or all 3).
The Tribunal and Bloodmoon expansion packs are REQUIRED for this mod!
The plug-in files for Weapon Rotate must also be selected (at the very least Weapon Rotate.esm), please have a look at the included "Read Me" files
(WeaponRotate1.0.txt) to understand how the racks for that mod are to be handled (these racks are used in Castle Avalon, Castle Kanthrock and Builder's Estate).
All 3 .esp files for Ald Vendras v3.0 are compatible with Illuminated Order and Korobal Island; as long as you keep Ald Vendras v3.0 loaded last.
Ald Vendras v3.0 is already compatible with Balmora Expanded (no patches needed). If you are running The white wolf of Lokken and Solstheim Castle plug-ins,
Ald Vendras v3.0 must also be loaded after them to avoid heavy landscape conflicts.
And yes, the needed version of Weapon Rotate is also included in the download of Ald-Vendras V3.