Add Related list which has relationship with 2 Tables

[New Developer_S]

Hi , 

Below is my use case.I looking for Best implementation methods for this.

I have 3 tables :

1.Business Service table ( cmdb_ci_service)

2.Knowledge table ( kb_knowledge)

3.Knowledge Template Table ( kb_template)

I have created a reference field called Business Service ( to Business Service Table )  in each of the 2 tables Knowledge and Knowledge Template .Now , KB article is linked to business service individually .

I want to add a Related List to Business Service table  (cmdb_ci_service) Table -

referably - Relation from above 2 tables ,

kb_knowledge and kb_template_knowledge.

 Use case is to create a Single related list for Business service table where it should get all KB articles related to That particular business Service only.

I have tried using array concatenation in relationship , but with that - all the KB articles are fetching - which is not an ideal output.

Is there another way of creating the relationship?

If so, Please can someone assist with the script?

Your assistance will be much appreciated.

Thanks in advance for your time and effort.

here is my script for Relation ship :

(function refineQuery(current, parent) {

var mergedArray = new ArrayUtil();

var KnowledgeArray = [];

var HowtoArray = [];

var knowledgeGR = new GlideRecord('kb_knowledge');

knowledgeGR.addEncodedQuery('workflow_stateNOT INretired,outdated^u_business_service_ref.nameISNOTEMPTY');;

knowledgeGR.addQuery();

while(knowledgeGR.next()) {

     KnowledgeArray.push(knowledgeGR.getValue("Business Service"));

}

/*

Do the same as above for Howto

*/

var howtoGR = new GlideRecord('kb_template_how_to');

knowledgeGR.addEncodedQuery('workflow_stateNOT INretired,outdated');

howtoGR.query();

while(howtoGR.next()) {

    HowtoArray.push(howtoGR.getValue ("Business Service"));

}

// Make a union of all arrays

mergedArray = mergedArray.concat(KnowledgeArray, HowtoArray);

current.addQuery('sys_id', 'IN', mergedArray);

//current.addQuery('sys_id','IN', KnowledgeArray,HowtoArray);

})(current, parent);