Purchase of Plot on past GPA transfer plot

Dear sir, i am Ramesh, residing in Bangalore, i am purchasing Plot in Hosur, the said plot has transfer in  the following stages, stage 1. Ist owner of the plots sold to Agent by GPA, stage 2. Agent sold the plot  to 2nd buyer through the Registration i,e sale deed.

Stage 3 The 2nd buyer sold to the 3rd buyer in same fashion by registration. Stage 4 Now we are planning to buy the said plot.

My question:

1. Whether ownership   got transfer through the GPA to agent  is valid?.

2. Whether in stage 2 and stage 3 buyers are having the full right against the property due initial ownership transfer to Agent through GPA.

3. whether Advice whether to buy this property.