Basic form is ~을 부탁하다. (ask) => 확인을 부탁하다 (ask to check) => 확인을 부탁(을) 드리다. (드리다 is used to sound formal or respecful) =>가능한지 확인을 부탁 드리다. (ask to check if...) => 참석이 가능한지 확인을 부탁 드리다. (ask to check if they can attend ..) => 관련자분들의 참석이 가능한지 확인을 부탁 드리다. 관련자분들의 참석이 가능하신지 확인을 부탁을 드립니다. => I would like to ask you to check (Or Please check) 확인을 부탁(을) 드립니다. => if the persons concerned can attend the meeting (or anything in the context.) 관련자분들의 참석이 가능하신지. If I literally translate "관련자분들의 참석이 가능하신지" into English, it would be "if it is possible for the persons concerned to attend the meeting". I am sure how you, native speakers, feel the difference between the two. the persons (사람들) + concerned (관련된, 관계된) : 관계자+분(added to sound respectful)+들(plural) attend : 참석하다 In fact, it's just a normal sentence we can hear in a business setting, but it still has some grammatical error. I would say 관련자분들의 참석이 가능한지 확인(을) 부탁드립니다. is better. Generally, it's not correct to put two objects like "확인을" and "부탁을" before a verb. Though not a few Koreans just make that mistake in their writing and it's just not a big deal, it's still an error if it's a very important document or professional writing. If there is anything you don't still understand, leave a comment. I will help you out as long as I can.