'adopt a grandparent' locally

Not sure whether this is allowed, but I'd love for our three children to have the opportunity to engage with a 'grandparent' figure on a regular basis as this is not something we can provide. Myself and my husband are fortunate enough to be able to provide quality time with our young family, but we feel they miss out on the benefits of engaging with an older 'family member'. We live in Nottinghamshire and would love to 'adopt a grandparent/ grandparents' if there are any persons out there who would equally welcome such a partnership ... or if anyone could advise us as to an agency which would be able to assist with this aim ... many thanks x