Yes. I'm not sure how much they'd add; I ran into an interesting observation about this with regard to estimating cows' milk production based on their relatives and on SNPs, where the comparison runs the other direction:

The R^2 values were converted to realized reliabilities by dividing by mean reliability of 2008 daughter deviations and then adding the difference between published and observed reliabilities of 2003 parent averages. When averaged across all traits, combined genomic predictions had realized reliabilities that were 23% greater than reliabilities of parent averages (50 vs. 27%), and gains in information were equivalent to 11 additional daughter records.

So if an old SNP chip can add that much information in terms of family records, the family can't matter that much.