Stacking in groups of 3 in bridge

This script stacks RAW + JPEG images, you'd need to modify it for your use but it would be the same framework. Just using a different way to determine which images to stack.

/*
Utility Pack Scripts created by David M. Converse ©2018-21

This script autostacks RAW+JPEG

Last modifed 6/7/2021

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#target bridge
if(BridgeTalk.appName == 'bridge'){
    var StackCmd = MenuElement.create('command', 'Stack RAW + JPEG', 'at the end of Tools'); //create new menu command
    }

StackCmd.onSelect = function(){
    try{
        var thumbs = app.document.thumbnail.children;
        var baseName = '';
        var baseLen = 0;
        for(var i = 0; i < thumbs.length; i++){
            if(thumbs[i].core.itemContent.canDoCameraRaw){
                baseName = thumbs[i].name.split('.');
                baseLen = baseName.length - 1;
                if(baseName[baseLen] != 'jpg'){
                    baseName.length--;
                    baseName = baseName.join('.');
                    for(var j = 0; j < thumbs.length; j++){
                        if(thumbs[j].name == baseName + '.jpg'){
                            app.document.select(thumbs[i]);
                            app.document.select(thumbs[j]);
                            app.document.chooseMenuItem('StackGroup');
                            app.document.deselectAll();
                            }
                        }
                    }
                }
            }
        }
    catch(e){
        alert(e + ' ' + e.line);
        }
    }

I have Photoshop scripts to batch layer in sets, say 30 images in sets of 3 to batch create 10 layered files... But not a Bridge script to create image stacks.