I have no personal experience, but looking online, it seems like alpine is pretty similar to Timothy Hay. The Timothy hay %’s are from “Oxbow”, and the Alpine is from “Padovan”. Timothy hay comes from meadows, while Alpine hay comes from mountains, and Alpine can contain a more varied bundle of grasses and flowers as well (based on research)

Alpine:
Crude Protein 8%
Crude Fat 2%
Crude Fiber 28%
Moisture 8%

Timothy:
Crude Protein min 7.00%
Crude Fat min 1.50%
Crude Fiber max 32.00%
Moisture max 15.00%

It seems like Alpine may be a party-mix of flowers and different grasses, so something I’d watch for and try to lessen is selective eating, if your rabbits end up just eating certain species in the mix they find are best. A great way to lessen this is not to throw out non-soiled hay they haven’t eaten, but to throw it back in the bag/your hay container, mix it all together, and re-distribute.

Since it’s a new hay and is grown in a different environment (different pollens, dust, etc..), try and transition into the alpine, rather than offering all at once. Start with mostly timothy and add a little alpine, then go from there.

— My most prominent suggestion is to return the alpine bag and purchase a timothy hay bag, and let your dad know what he needs to look for specifically. It’s good for you and anyone associated with your rabbits’ care to know the names of what type of hay, pellets, etc.. are needed.