You can assign 1, 2, or 3 throdama (with the same ready pheremone) to a pregnant female to get a baby with a specialized morph. These morphs look different than normal throdama, can't breed, and have certain special abilities Depending on how many you assign, the baby will get more or less special abilities.
For example, say you have one throdama with a ready Warrior pheremone, and you assign it to use that pheremone on a pregnant female/her baby. The baby will have the Warrior morph (check Skins -> Throdama to see what that looks like), as well as the trait Spikes (increases blow/rush damage and critical strike chance). If you use two Warrior pheremones, the baby will additionally get Venemous Spikes, which gives them a chance to poison an enemy in battle. And if you use three warrior pheremones, you get a Grade 3 Warrior, which will have Stench (increases dodge chance by a lot) as well as the other traits.
So it's a tradeoff--if you have three throdama with ready Warrior pheremones, you can make three Grade 1 Warriors, or one Grade 3 warrior. (Or one Grade 2 and one Grade 1.) It's a quality/quantity choice.
You can't assign babysitters to use different pheremones on the same baby--you can use one, two, or three Warrior pheremones, but not one Warrior pheremone and one Scout pheremone.
The Beast Codex has more information on the different morphs and grades: https://beastkeeper.com/beast-codex#q2