Guys don't beat me for saying this.
I don't think malhar knows the truth. As per today epi kalayni knows that none at ahalkya niwas supports her pregnancy and are hell bent on killing her child. And I think she trust that malhar won't let it happen. But I think amidst today keecha Tani by Kaka kallu will fall unconscious malhar who reaches there will take her to hospital and then this scenes and abortion drama but I believe she will think that even malhar wants the kid dead hence would decide to run away from AN until she gets the child safley delivered beacuse as of now she can't trust anyone in ahalkya niwas .
I believe atharva as mastani Bai would offer he r shelter until her delivery. So this way atharva can keep malhar kalayni away and chances of surrogacy truth getting out will be less too. Malhar would be madly running around to search kalayni and entire AN niwas will be in worry so atahrva can utilize the chaos to run away right.