Is consuming Nido powdered milk permissible (halal), knowing that soy lecithin is one of its ingredients and that soy lecithin is halal?

There is no harm for a Muslim in using this milk or other similar types; for the unknown is like the non-existent, and there is no need to inquire about it. The Permanent Committee has issued a fatwa (definition) permitting the consumption of cheeses made with rennet without inquiring about its source, and Sheikh Ibn 'Uthaymeen affirmed that the basic principle concerning everything Allah has created for us on earth is permissibility. One should not pay attention to doubts raised about the milk's ingredients. If its source is plant-based, it is permissible. If it is animal-based, then it is either from an animal ritually slaughtered and permissible, or from an animal whose consumption is forbidden but its nature has transformed, or it has been immersed and consumed within the milk. In both cases, its use is permissible.