To transfer one's own kamma to another being requires a certain strength and agility that is present only in certain kusala cittas but entirely absent in all akusala ones. If one ever had a wish to bestow one's own evil kamma upon another being, then by definition the citta at that moment would be akusala, hence incapable of effecting any sort of kamma transference. For a more detailed discussion of this point (and many others on this same topic) see the Milindapa˝ha's Pubbapetādisapa˝ha (Mil. 294-7 = I.B. Horner, Milinda's Questions II. 123-8).
I agree that the word "transfer" is not exactly the right term. Inviting others to rejoice, that makes more sense. If that person rejoice in it, then he/she will create his/her own kamma and will receive its result.
You are discussing two different things here. Inviting others to rejoice in something meritorious that one is doing is called pattidāna. Occasionally this does get misleadingly translated as "transferring merit", but it would be better to reserve this expression for pu˝˝a-uddissana, which is something else entirely.
Pu˝˝a-uddissana is an act carried out by humans for the sake of alleviating the sufferings of one of the four types of hungry ghost. The four types are:
1) vantāsika petas: those who relieve their hunger and thirst by eating vomit.
2) khuppipāsī petas: those who have no means to relieve their hunger and thirst.
3) paradattūpajīvī petas: those who relieve their hunger and thirst by receiving offerings of merit from humans.
4) nijjhāmataṇhika petas: those who relieve their hunger and thirst by stealing merit from paradattūpajīvī petas.
Most commonly one will perform some meritorious deed and then transfer the merit to one's deceased relatives and ancestors. If the beings concerned happen to have been reborn as paradattūpajīvī petas then one's merit transference will relieve their hunger. If they have been reborn somewhere else then it won't be of any use to them. This leads King Milinda to ask Nāgasena if the transferred merit will go to waste. His answer is no: the merit will simply remain with the person who made it; he will also accrue additional merit for his kusala intention to help his departed relatives.