See if for completion OC is there and registry is pending only for dues and builder is ready to pay same.you can enter into triparty agreement with builder and current seller wherein the current seller can give indemnity bond that in case registration is not done in stipulated time he  will pay complete amount back.

Yes, you can go ahead and buy. In this case merely the allotment is being  transferred from the current allottee in your name. However, in accordance with the UP Apartments Act, a flat cannot be occupied in absence of completion certificate. SO, check with the builder if he has completion certificate, legally you can take possession of this flat only if the builder is having the completion certificate. 

Don’t purchase the flat as title is not clear and marketable 

2) if registered sale deed cannot be executed in your name don’t waste your hard earned money in purchase of flat 

You need to file a consumer complaint and take direction from consumer court for the same

Even Possession is the prima facie evidence of the ownership but without valid registration the possession is illegal. so don't purchase the flat. 

1.  SINCE it is a Re-Sale Flat, you can prefer to conduct the following:

a)  Pay the outstanding dues of the Authority,

b)  Builder has to execute Agreement between Builder + Original Owner + yourself, by making the earlier owner as "Confirming & Consenting Party" and taking his signature before the Registrar of Sub-Assurances.

c) The above will legalize the deal. Note that Builder CANNOT execute any deal directly with you, since it will be a criminal offence for the Builder.

Dear,

        We purchase a house for ourselves and spend all self money in that,

         and want peaceful life there.

         As you mentioned, it will take time and title is not cleared, 

        so in my view spend in another project and don't purchase this flat.  

Deal will face set back and you will suffer money lose. Until builder not clear the dues, purchase not advisable. And in most of such cases, builders are facing insolvency and criminal prosecution. Many in NOIDA.

No it is not safe to purchase flat in this situation.

You should invest in the property where you can easily get the ownership by registered sale deed. 

It is not advisable to buy a proeprty whose registration cannot be done while purchasing it.

In fact the property was already purchased by another buyer whereas he is trying to quit the property for obvious reasons, so before getting trapped into a legal quagmire, better wait for the registration to open after which you may plan to buy the property.

1. As per the information mentioned in the present query, makes it clear that the owner doesn’t have the registry and builder is ready to give you the possession without having registry been registered.
2. I would advice you to not to take the possession till the time you got all the legal papers as if anything goes wrong between the owner and builder then you may be put into trouble for no fault at your end.
3. There have been cases in which the new buyers are put in trouble due to non payment of dues and then burden comes on the person buying as the authorities are having law in their favour as to get the dues cleared from the person who is now the owner.