ZWJ sequences for custom images

[Crissov]

Please define Emoji ZWJ Sequences for custom emojis, so they become interchangeable. That would be perfectly valid according to UTR#51.

Example emoji.json snippet

{
    "emoji": "⛺️\u200D🏔"
  , "aliases": [
      "basecamp"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "⛺️\u200D⛰"
  , "aliases": [
      "basecampy"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "😁\u200D🎀"
  , "aliases": [
      "bowtie"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "😏\u200D👾"
  , "aliases": [
      "feelsgood"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "💀\u200D👾"
  , "aliases": [
      "finnadie"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "😈\u200D👾"
  , "aliases": [
      "goberserk"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "😑\u200D👾"
  , "aliases": [
      "godmode"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "🤕\u200D👾"
  , "aliases": [
      "hurtrealbad"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "🤓\u200D💯"
  , "aliases": [
      "neckbeard"
    ]
  , "tags": [
       "custom"
   ]
  }
, {
    "emoji": "🐱\u200D🐙"
  , "aliases": [
      "octocat"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "😡\u200D👾"
  , "aliases": [
      "rage1"
    ]
  , "tags": [
       "custom"
   ]
  }
, {
    "emoji": "😡\u200D💢\u200D👾"
  , "aliases": [
      "rage2"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "😡\u200D💢\u200D💢\u200D👾"
  , "aliases": [
      "rage3"
    ]
  , "tags": [
       "custom"
   ]
  }
, {
    "emoji": "😡\u200D💢\u200D💢\u200D💢\u200D👾"
  , "aliases": [
      "rage4"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "🐿\u200D🕴"
  , "aliases": [
      "shipit"
    , "squirrel"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "🤔\u200D👾"
  , "aliases": [
      "suspect"
    ]
  , "tags": [
      "custom"
    ]
  }
, {
    "emoji": "😬\u200D💢"
  , "aliases": [
      "trollface"
    ]
  , "tags": [
      "custom"
    ]
  }

[mislav]

What is UTR#51?

[Crissov]

http://unicode.org/reports/tr51/