Where to specify visa rejections in Tier 1 extension applica

My dependents Entry clearance under Tier 1 (General) was initially rejected under section 320(7B). Later the refusal was overturned by local embassy and they were granted Entry Clerance. Now I am applying for Tier 1 Extension. Where in the dependent application form can I include these details? There is no question on previous visa rejections.
Should I include them in cover letter or leave them completely?

Thanks [/quote]