What Happens If You Do Not Offer Ud-hiyah for Years?

What is the ruling on charities slaughtering udhiyah (sacrifices) without mentioning the donors by name at the time of slaughter?

His sacrifice (udhiyah) was slaughtered without him giving any instruction to that effect

Is his and his brother’s udhiyah (Eid sacrifice) valid, when their father is spending on them and he does not pray?

Ruling on playing with the sacrificial animals for fun, and enjoying watching the rams butt heads and fight with one another

The owner of the udhiyah says Bismillah and says niyyah the out loud, but delegates another man to do the slaughtering

Is it valid for both spouses to contribute to the price of a sheep for udhiyah (sacrifice)?

He appointed him to slaughter the udhiyah, but Eid in the country of the person appointed to do that comes before Eid in the country of the one who appointed him

Buying a share (in an animal) for the udhiyah, sharing with one who wants to offer a wedding feast, and the minimum amount that is required for the wedding feast

Is Udhiyah Obligatory?