Using Karabiner Elements, can rules interact with each other?

Question

I'm trying to achieve something along the lines of: If holding down left_command and pressing j, it would activate left_arrow and If holding down left_command + s and pressing j it would activate left_shift + left_arrow. So that you could navigate using jkl; on your keyboard, functioning like the arrow keys, and then hold down s to simulate shift if you wanted to while using jkl; as arrow keys.

I managed to create these two rules separately, but they don't interact and I was wondering whether there's a setting or an easy way to do that?

My current attempt:

"manipulators": [
{
    "from": {
        "key_code": "j",
        "modifiers": {
            "mandatory": [
                "left_command"
            ],
            "optional": [
                "any"
            ]
        }
    },
    "to": [
        {
            "key_code": "left_arrow"
        }
    ],
    "type": "basic"
},
{
    "from": {
        "key_code": "s",
        "modifiers": {
            "mandatory": [
                "left_command"
            ],
            "optional": [
                "any"
            ]
        }
    },
    "to": [
        {
            "key_code": "left_shift"
        }
    ],
    "type": "basic"
}]

What happens is: If holding down left_command and s while then pressing j, it will just print "J" since that's essentially what that bottom rule says in isolation, but I would like it to then apply the top rule and go one to the left instead, while then holding down shift.

Is this possible in any way?