How can I remove the condition on my EB-5 conditional green card through I-751 with a pending I-829?

You cannot remove conditions on the EB-5 conditional green card through I-751. It is strictly done through I-829. While your waiting dilemma is understandable, I-751 cannot be used to assuage the long wait of I-829.

No.

Complicated, but to proceed through marriage you need to do the complete case and ultimately abandon your two-year card.

This may not be the best option for you. Because you are already a conditional permanent resident with a pending I-829 case, you may extend your status with I-551 stamps that allow you to work and travel while you await a decision on your I-829 case. You cannot use I-751 with a pending I-829. You have to file a family-based green card case first, have it approved and obtain a family-based two-year green card first through consular processing and surrender your current permanent resident status first. Then you can file I-751 within the 90 days before expiration of your two-year marriage-based green card. It is advisable that you now inquire with your EB-5 attorney to make an inquiry with the USCIS EB-5 unit since it appears your I-829 case is extremely outside normal processing times.

No, you may not file an I-751 to remove the conditions on your I-829. I-751 petition is marriage-based. Since your I-829 has been pending for five years, you may want to seek other venues to force USCIS to adjudicate it, i.e., litigation, provided there are no significant issues in your I-829.

It may be possible to just withdraw the I-829. I would want to look at the entire immigration history first.

No, you cannot file an I-751 to remove the conditional permanent residency that is based on an EB-5 immigrant investor processing. The I-751 is only applicable to a marriage-based conditional permanent residency, and can only be used to remove the conditions if you processed and obtained your green card through your marriage. If you have a pending I-829, you will need to complete your processing through that petition.

If you already have conditional residency it would be redundant to reapply for permanent residency once you marry. In fact, it would be impossible unless you were to renounce your current status. The proper thing to do would be to follow up on why your I-829 petition to remove conditions is still pending for more than five years. If in fact your conditions are not going to be removed for some valid legal reason, you would then seek to reacquire conditional residency based upon your marriage, but to do so you effectively would have to renounce your current status.

First, your EB-5 lawyer and the regional center should explain why I-829 is taking so long. Since the current processing times is 30 months, you have a basis for making an inquiry through USCIS for adjudication and keep bugging them. As to your marriage to U.S. citizen, the immigrant petition is I-130 a family-based application, which does not have any effect on your employment-based application of EB-5, as they are both the immigrant visa category. However, because you are already a permanent resident, albeit a conditional one, it may confuse the bureaucrats at the USCIS if you file I-130 and I-485 concurrently. I would suggest that your lawyer push for a decision on I-829 and file only I-130 first before submitting I-485 only after that is approved. If you get a conditional green card through marriage and you are still married after two years, the removal of that condition should not be a problem.

No you cannot use marriage to get an I-829 approved. You have to file a new marriage-based petition and designate consular processing. Then you have to surrender your current green card and start again as a conditional resident through marriage.