Modifying the intention when performing Hajj

Q 1: I am a Saudi woman who performed obligatory Hajj (pilgrimage) some years ago. During my Hajj, the day of standing at `Arafah coincided with Friday. After one or two years it was said to me: Next year, Hajj will coincide with Monday, and according to a Hadith attributed to the Messenger (peace be upon him): Whoever performs Hajj twice and his standing at 'Arafah coincides with Friday and Monday, the reward of his Hajj will be equal to the reward of a hundred times of Hajj wherein standing at 'Arafah occurs on a day other than these two days. Therefore, I desired to obtain this great reward, and I set out to perform Hajj. On the way to Hajj, it was said to us: Hajj will not coincide with Monday as we were expecting. Then I asked: Is it allowed for me to change my intention of Hajj and make it on behalf on my late father who was killed before he could perform Hajj? I was informed that there is no prohibition to do that, and therefore, I made the intention of Hajj to be on behalf of my father in the place of his obligatory Hajj. However, I am in doubt regarding the legality of modifying the intention. I also authorized one of my Mahrams (spouses or unmarriageable relative) to throw the pebbles at the Jamarat (stone pillars marking the pebble-throwing area, Jamarat-ul-`Aqabah being the closest to Makkah) after I had thrown them the first time. My questions are as follows:1- What is your Eminence's opinion regarding modifying the intention of Hajj to be on behalf of my late father? (Part No. 10; Page No. 121) 2- If you have any comments, please guide me to what I should do.3- What is your Eminence's view regarding authorizing one of my Mahrams to throw the pebbles after my initial throwing of them in the first time? 4- Please provide me with a correct opinion concerning what I should do, keeping in mind that I performed Hajj twice some years ago.