Krishna also had insisted Yudhishtira to lie about Drona vadh, as it was evident that Drona (knowing the capabilities of his son Ashwatthama) may not trust Bhima alone and may approach Yudhishthira to seek the truth.

My question "Meaning of Krishna's advice to Yudhisthira before Drona Vadh" is on the same event but different aspect. Its source actually answers your question:

Govinda, knowing that Drona, that foremost of warriors, was capable of sweeping all the Pandavas off the face of the earth, became much distressed. Addressing Yudhishthira he said, 'If Drona fighteth, filled with rage, for even half-a-day, I tell thee truly, thy army will then be annihilated. Save us, then, from Drona. under such circumstances, falsehood is better than truth. By telling an untruth for saving a life, one is not touched by sin. There is no sin in untruth spoken unto women, or in marriages, or for saving king, or for rescuing a Brahmana. ₁

_{1: This verse is omitted in the Bombay text. There can be no doubt, however, about its genuineness.}

Somewhere Krishna also advises to Arjuna that to establish Dharma, if Adharma is required then it's better. For example the event of Bhurishrava vs Satyaki:

_{Krishna told Arjuna, “Burishwara is going to kill Satyaki. You must get Burishwara first before he kills Satyaki.” Arjuna said, “How can I do that? Burishwara is fighting with Satyaki. Shooting him now would be against the Kshatriya dharma.” Krishna told him, “Satyaki has come here only to fight for you. How can you let someone kill him now? Save him.” Arjuna said, “No. It is against the law.” Then Burishwara pulled out his sword in order to decapitate Satyaki. Again Krishna said, “Your friend, who put his life at stake for you, will be slaughtered now if you don’t reach out to him. Will you let him die like this? What kind of dharma is this?” All this time, Arjuna’s arrow was aimed at Jayadrada. When Burishwara was about to decapitate Satyaki, Arjuna turned and shot the arrow at Burishwara. Burishwara’s right hand got severed. He looked around and said to Arjuna, “How could you do this? While I was fighting with another man, you shot me from behind and severed my hand? Anyone who has Kshatriya blood in him wouldn’t do such a dastardly act. I know you wouldn’t have done this by yourself. This cowherd with whom you are must have influenced you.” Arjuna’s anger flared up, and he said, “Yesterday, when you, a great warrior, joined many others to surround my son, a 17-year-old boy, and stab him from behind, where was your dharma? What are you talking about now?” Ashamed of the act that he had committed the day before, Burishwara put his head down. He went next to his chariot and sat down in lotus posture.}

Abhimanyu was killed by cheating when Drona was the Kaurava Army commander. Angry Drona ultimately would have got victory for Duryodhana, who was epitome of Adharma. This was the reason, Krishna advised Yudhishtira to lie.
Ofcourse there would be bad fruit for such misdeed, which Yudhishtira had to go through before entering Heaven. But according to Krishna it was worth for establishing the Dharma.

BG 18.66

sarva-dharmān parityajya
mām ekaṁ śaraṇaṁ vraja
ahaṁ tvāṁ sarva-pāpebhyo
mokṣayiṣyāmi mā śucaḥ

Abandon all varieties of Dharma and just surrender unto Me. I shall deliver you from all sinful reactions. Do not fear.