I opted for a service in the end.

  import type { 
    AccordionChildMap,
    AccordionStates,
    AccordionData,
    AccordionProps,
    AccordionKeys,
    AccordionAction,
    AccordionPanelState,
  } from '@/types/global';

  class AccordionServiceInstance {
    #childMap: AccordionChildMap;
    #datas: AccordionStates;
    #props: { [key: string] : AccordionProps };
    #actionHandlers: { [key: string] : AccordionAction }
    #nameIndex: number;
    
    constructor() {
      this.#childMap = {};
      this.#datas = {};
      this.#props = {};
      this.#nameIndex = 0;
      this.#actionHandlers = {};
    }

    registerParent(data: AccordionData, isVert: boolean, allOpen: boolean) : string {
      console.log("ParentHeight: " + data.height);
      const parentName = "accordion" + this.#nameIndex++;
      this.#props[parentName] = {
        isVert: isVert,
        allOpen: allOpen,
      } 
      this.#datas[parentName] = data;
      return parentName;
    }

    registerChild(childName: string, onChange: AccordionAction, headerHeight: number) : string {
      
      let foundParent = "";
      console.log("set headerHeight: " + headerHeight);
      
      const keys = Object.keys(this.#datas)
      for (let i=0; i < keys.length && foundParent == ""; i++) {
        const key = keys[i];
        const parentKeys = Object.keys(this.#datas[key].state);
        if (parentKeys.indexOf(childName) > -1) {
          foundParent = key;
          this.#childMap[childName] = key;
          this.#actionHandlers[childName] = onChange;
          this.#datas[foundParent].headerHeight = headerHeight;
        } else {
          console.log("AccordionService could not find parent for: " + childName);
        }
      }
      return foundParent;
    }

    getPanelHeight(childName: string) : string {
      const stateName = this.#childMap[childName];
      const data = this.#datas[stateName]
      const state = data.state;
      const props = this.#props[stateName];
      const childState = state[childName];
      const childCount = Object.keys(state).length;
      return (childState.disabled || 
        !childState.open) ? "0" :
          props.allOpen ? "auto" : (data.height - childCount * (data.headerHeight + 8) + "px");
    }

    getChildState(childName: string) : AccordionPanelState {
      const stateName = this.#childMap[childName];
      return this.#datas[stateName].state[childName];
    }

    getChildProps(childName: string) : AccordionProps {
      const stateName = this.#childMap[childName];
      return this.#props[stateName];
    }

    getData(parentName: string) : AccordionData {
      return this.#datas[parentName];
    }

    setHeight(parentName: string, height: number) : void {
      console.log("set height: " + height);
      this.#datas[parentName].height = height;
      const state = this.#datas[parentName].state;

      Object.keys(state).forEach( (x) => {
        console.log(x + "| open:" + state[x].open + "| disabled:" + state[x].disabled)
        this.#actionHandlers[x](state[x].open, state[x].disabled);
      });
    }

    changeChildState(childName : string, property: AccordionKeys, value: boolean) : void {
      const stateName = this.#childMap[childName];
      const props = this.#props[stateName];
      const state = this.#datas[stateName].state;
      if (!props.allOpen && property == "open" && value) {
        Object.keys(state).forEach( (x) => {
          if (x == childName) {
            state[x].open = true;
          } else {
            state[x].open = false;
          }
        });
      } else {
        state[childName].open = value;
      }
      Object.keys(state).forEach( (x) => {
        console.log(x + "| open:" + state[x].open + "| disabled:" + state[x].disabled)
        this.#actionHandlers[x](state[x].open, state[x].disabled);
      });
    }
  }

  export const AccordionService = new AccordionServiceInstance();

Utilizing the control:

 <AccordionControl :state="{
    colorWheel: { open: true, disabled: false },
    colorMixer: { open: false, disabled: false },
    colorSelector: { open: false, disabled: true },
  }"
 >
   <AccordionPane panelName="colorWheel">
      <template v-slot:header>
        <h2>Create Color Scheme</h2>
      </template>
      <template v-slot:content>
        Stuff here
      </template>
    </AccordionPane>
    <AccordionPane panelName="colorMixer">
      <template v-slot:header>
        <h2>Color Mixer</h2>
      </template>
      <template v-slot:content>
        <h1>Stuff here</h1>
      </template>
    </AccordionPane>
    <AccordionPane panelName="colorSelector">
      <template v-slot:header>
        <h2>Assign / Select colors</h2>
      </template>
      <template v-slot:content>
        <h1>Stuff here</h1>
      </template>
    </AccordionPane>
  </AccordionControl>

There is more to be elaborated on in the answer, like the stylesheets and the controls, so I hope you can see this:

edit: new public link provided, you should have access to it.

https://codesandbox.io/p/github/geewhizbang/iconBuilder/main?layout=%257B%2522sidebarPanel%2522%253A%2522EXPLORER%2522%252C%2522rootPanelGroup%2522%253A%257B%2522direction%253A%2522horizontal%2522%252C%2522type:%2522PANEL_GROUP%2522%252C%2522id:%2522ROOT_LAYOUT%2522%252C%2522panels%2522:%255B%257B%2522type%2522%253A%2522PANEL_GROUP%2522%252C%2522JPSCdi..."

I trust this isn't a workaround.