What is the ruling on taking expensive pigeon eggs and placing them under another inexpensive pair, while discarding the eggs of the inexpensive pair, in order to accelerate the production of squabs from the expensive pair, and repeating this process multiple times, then later leaving the eggs to the expensive pair?

There is no legal impediment to placing expensive eggs under inexpensive pigeons for the purpose of benefit, as the fundamental principle concerning a Muslim's disposition of their possessions in a way that achieves a recognized legitimate benefit, and involves no harm or prohibition, is permissibility. As for discarding inexpensive eggs, it is not permissible because it constitutes a waste of money, which is prohibited by Islamic law. Rather, one should utilize them or give them to those in need. If it is not possible to utilize them or if they are no longer suitable, then there is no harm in discarding them.