Investors & landlords

Say,  1 million is what I borrow and 75% is self occupied area and 25% is occupied by ADU (area which is rented for residential purpose), allocating 75% debt to self occupied primary and rest to ADU is straightforward.

However, is that a must? As in, say 1.2 million is the price of the entire home and  200K is down payment. It is clear that self occupied primary  area price is 900K and that of the ADU is 300K. Now, do I have an obligation to split my down payment too in the ratio 75:25?  If I consider entire downpayment towards my primary, then loan on primary is 700K and that on ADU is 300K.  Please ignore whether this is more/less tax beneficial that splitting the downpayment in the ratio 75:25.

Comments from you would be really helpful.