i mean, to unlock position is to gain 4 heart of girls and some s3x exp point. i dont get any new position and bottommost option is mating press, but when i am playing studio i see h position like dogy flying but i cant find that position in main game.
The Hearts are related to the level of
Trust and to dialogues whit the girl. When you reach 3 hearts she gain some personality and sex attributes and you can add/change these attributes whit whatever skill you have found.
Sex experience is related to
Lust level , the higher her sex experience is the faster her lust raise.
Both these values don't unlock new H positions. You can have all H positions available for a fresh new girl, what you need is the location and the furniture linked to the H position.
E.g. for the scissoring M+F position that you have in the church' bench in HS2, in AI-S you need a particular bench (red and black) and select the central seat as you H position.
When you design your homes, keep in mind that many furnitures/object have an
action point that is linked to some H positions, you will learn them whit experience.
Studio has some custom made H poses that are not implemented in the main game, those are only poses for making shots or VN.