Can I demand that only A participates in the move-out inspection, or can B, C, D, and E also insist on being present? I think the move-out inspection is only a matter between A and the landlord.

According to the Danish Rent Act § 187, subsection 3, you must notify A in writing about the move-out inspection with at least 1 week's notice — you are only obligated to notify A, as A is the one who has the lease agreement with you. B, C, D, and E have no contract with you, and you do not need to notify them.

However, this does not mean that you can exclude B, C, D, and E from participating. A, as a party to the inspection, has the right to bring an advisor or support person, and there is no legal basis for you as the landlord to demand that only A is present if A wishes to have others with them. The responsibility and payment obligation resulting from the inspection (repairs, deficiencies, etc.) lie solely with A, regardless of who is present.