Offered redundancy/new role ref future redundancy

Hi all
Been working for the business for 8 years and just been offered redundancy or an alternative position at a lower grade, however question I have is if I accept the new position that actually has some of my old job role responsibilities /accountabilities in it and the company later on say in a years time decides to go through another round of redundancies, would I still be eligible for a payout as I will still have been employed at that point for 9 years with the same company however technically I have only been in the new job role for 1 year. .....does the 2 year qualification for a payout apply to length of service or to the job role ?
Thanks in advance for your replies