(court considers defendant’s motion to dismiss for abstention under doctrine established in Colorado River Water Conservation Dist. v. U.S., 424 U.S. 800 (1976); pending state court action regarding the administration of a family farm trust and allegations of a breach of fiduciary duty and legal effect of daughter’s changes to distributions in trust document while the benefactor was incapacitated; allegations also regarding propriety of distribution of federal estate taxes among beneficiaries; court held factors were in favor of abstention, but stayed proceedings rather than dismissed suit).