NGRX/data how to modify / update additionalCollectionState

Question

I am facing one issue and unable to resolve:

I am using ngrx data with following:

const entityMetadata: EntityMetadataMap = {
    forReports: {
        entityDispatcherOptions: {
            optimisticUpdate: true,
        },
        additionalCollectionState: {
            selectedForReports: []
        }
    },
};

& registered:

export class ForReportsModule {
    constructor(
        private eds: EntityDefinitionService,
        private entityDataService: EntityDataService,
        private forReportsDataService: ForReportsDataService
    ) {
        eds.registerMetadataMap(entityMetadata);

        entityDataService.registerService("forReports", forReportsDataService);
    }
}

Store:

What I want to achive is to simply modify selectedForReports in-store with a function.

for example:

function updateSelect(value) {

...
...
selectedForReports = value;
...
}

I tried to go through official docs of ngrx all stackoverflow post github posts but none of this works.