Urgent: Need related list to show different columns per record type + limit "New" button

[supriya1kum]

I have the OOTB Demand application. On the Demand form, once a demand is submitted, there's a list-type field called Demand Assessment with three choices:

• Infrastructure Assessment
• AI Assessment
• BIA Assessment

Users can select one or more of these. When the demand moves into the Screening state, a Demand Task record is auto-generated for each selected choice, with the task's Short Description set to match the choice (e.g. "Infrastructure capacity assessment," "AI Use case capacity assessment").

I've built a custom table, Demand Assessments, extended from Task, and added it as a related list on the Demand Task form so users can log the actual assessment details. This custom table has different sections of fields depending on the assessment type — e.g. for Infrastructure it has Infra Area, Subcategories, Estimated Cost, Estimated Quantity, Business Criticality, RTO, RPO, HA/DR fields; AI and BIA assessments have their own separate sets of fields.

Problem 1: Related list always shows the Infrastructure columns

No matter which Demand Task I open — whether it's the Infra one, the AI one, or the BIA one — the Demand Assessments related list on the Demand Task form always displays the same set of columns (Infra Area, Subcategories, Estimated Quantity, Estimated Cost (AED), Cost Included in Initial Demand Scope).

What I need instead: when the Demand Task is for AI Assessment, the related list should show the AI-specific columns; when it's for BIA, it should show BIA-specific columns; and only for the Infra Assessment task should it show the Infra columns as it does now.

I've attached screenshots showing:

• An Infra-type Demand Task (DMNTSK0001147) with the related list showing infra columns — expected.
• An AI-type Demand Task (DMNTSK0001150) — but the related list is still showing the same infra columns instead of AI-relevant ones.

Problem 2: Need to cap the number of records creatable in the related list

On the Demand Assessment form, there's an Infra Area field and a dependent choice field Subcategories — the options available in Subcategories change based on what's selected in Infra Area (predefined mapping).

What I need: the maximum number of Demand Assessment child records a user can create under a given Demand Task should equal the number of Subcategory options available for the Infra Area they picked. Once the user has created that many records, the New button on the related list should no longer be available — for that Demand Task.

The same rule needs to apply independently for AI Assessment and BIA Assessment tasks, each with their own logic for what determines the max count.

What I'm looking for

• Any existing approach / best practice for showing different related-list columns based on the type of parent record (Demand Task assessment type).
• Any reliable way to dynamically cap and hide the "New" button on a related list based on a count comparison against a dependent choice list's available options — ideally something that also works consistently between classic UI and Workspace, since we use both.