fishy MMT, why they r asking......

On booking detail can I put my first SIM number and my original name with doing booking from my second account.

In DeTAils

I have basically 2 Sims.
1 new and 1 old .
on the old I have make MakeMyTrip account , Got bonus mmt wallet and used in 2015 now I have got a new sim in 2016 and new device also, I downloaded MakeMyTrip app and registered with new sim they have given wallet bonus. I have to use that ,
now
why they are asking that for whom you are booking,
for self or for other ,
now the main thing is that a new sim is not in service it is physically damaged and I have no time to change it but ,

I want to utilise that Sign UP bonus amount

I have login ID password with that same of mmt account now, and the time of mmt booking they are asking that you are booking for yourself or someone other

now if I am saying that I am booking for myself and putting same details as a first account they will have objections ???

and now what to do and why they are asking like that I have no connectivity with the new sim so should I put mark that I am doing for someone else

IS there is any dangerous by doing that

please guide me and explain in detail thanks in advance for general stands for reply