When was the I-130 filed? The notice should list a "priority date" on it; what is that date?
A married child of a US citizen is in the F3 category. Assuming your parents were not born in Mexico or the Philippines, visa numbers for F3 category are currently available for priority dates in Nov 2005 or before. (In other words, the wait from the filing of I-130 to visa availability is more than 12 years). You can check each month's
visa bulletin yourself.
You haven't told us what the petition's priority date is, but probably it was after 2005 and thus is still waiting for a visa number to become available, and you haven't missed anything yet. When a visa number is close to being available, your dad and grandpa should be contacted about the next steps, assuming that consular processing was selected on the I-130 (it most likely was), and assuming that you guys haven't changed addresses and failed to notify them.
You guys are doing Consular Processing at a US consulate outside the US for an immigrant visa. You will not do anything with I-485, which is for Adjustment of Status, the process of getting permanent residency from inside the US.
At the time that your dad can immigrate, his spouse and his unmarried, under-21 children at that time can immigrate as derivative beneficiaries. The problem is that you are all over 21 and one is married. The one that's married definitely cannot immigrate as a derivative beneficiary. The other ones who are unmarried but over 21 might be able to immigrate as derivative beneficiaries, depending how how much they are over 21, and how long the I-130 petition was pending. Under CSPA (the Child Status Protection Act), they look at the child's age at the time a visa becomes available, and subtract the amount of time the I-130 petition was pending (i.e. the length of time from when the I-130 was filed until the I-130 was approved); for example, if the I-130 took 2 years to approve, that means the children do not "age out" if a visa becomes available before they turn 23.
If you or your siblings cannot immigrate, your dad (or mom) can still petition you after they immigrate. Immediately after they enter the US with their immigrant visa, they are permanent residents, and can immediately petition their unmarried children. Note that permanent residents cannot petition married children, so the sibling who is married cannot be petitioned until one of your parents becomes a citizen. The rest of you can be petitioned as unmarried over-21 children of a permanent resident, in the F2B category, with a wait for visa numbers of around 7 years. And you cannot get married during this time, or it will void the petition as permanent residents cannot petition married children (well, you cannot marry until after the petitioning parent becomes a citizen, but even then, married child of a citizen has a much longer wait).
