My Grandchildren are 18 months and 31/2 years old.  I have been involved in my Grandsons life (2-8 times a month we do activities and sleep overs).  When my granddaughter was born I helped out by taking my grandson whenever possible.  I have not spent one on one time with my granddaughter since she was born.  My daughter in law (according to my son) does not want them seperated.  He stated that he didn't agree with this, but is respecting her opinion.  I am not certain about this position.  I am a single grandparent and feel as though I am unable to bond with her the way that I would like to.  There is also the problem of age appropriate activities.   I think it is equally important that they have their own time, as well as time spent together with me.

I also respect their decisions and do my best to keep my opinions to myself.  This is the first time that I have felt at a loss.  Is this normal or is there something else going on?

I also think it is important that the children do individual things from time to time and don't live in each others pockets. Children need their own identities and friends. As you say, they should be doing age appropriate activities and it is not always possible to find an activity suitable for both, although you can often adapt to suit.
How do you think your daughter-in-law is since the last birth. Has anything else changed. Could she perhaps have some issues like post-natal depression going on.
Another thought is that do you think it would be possible for you to take both children if you were given the chance? That way they would not be separated, but it would be a lot of work for you.
Have you talked to your DIL about how you feel?

Thank you for your response. It helps just to know that I'm not too off base. I do take the children together, at least twice a month. I love being with them and wouldn't let this situation stop our time together. I do, however, feel sad when they leave because I have spent the entire time going back and forth between the two of them while they vie for attention. The most enjoyable time is when they eat!!!! Not age related. I certainly don't object to having them togather, I just miss the time alone with them. I only have one child (my son), but I have two siblings and we did not do everything together. I appreciate any help from the parent's perspective. My DIL is a bit defensive when it comes to the children.

I guess that a lot would depend on how your DIL was brought up too. We usually reflect our childhood in our own parenting. Does she have siblings? Perhaps she thinks it might cause some kind of favouritism too, but if you could reassure her that both children would get equal quality time with you. When you have both of them however, it would give her and your son some nice quality time alone which is also very important to their marital health.
I hope it all goes well for you. Have fun with those two.

Gecko, I don't think you are off base at all. Unfortunately, though, you do have to respect your son and DIL's wishes. It's hard not getting defensive w/ your own children. My father is by himself since my mom passed away, and since then, he spends a lot of time w/ my boys (ages 5 and 3 1/2). He's a wonderful grandfather, and my sons adore him. However, I've had to set my dad straight on a few things. My dad feels that kids learn from their actions and life experiences, which is true, but when it comes to safety, like setting rules about running in the street, I feel I have to step in. Today's world is very different from when I was a little girl, and although I try not to be too over-protective a parent, I am very cautious about certain things. I wldn't focus so much on your DIL's opinions. Enjoy the time spent w/ your grandchildren, however that may be. They grow up so fast, and before long, you'll wonder where the time went. Have fun!

Thanks for your time and perspective