Drafting Of Will

I am a widow. I have some property in UP ( Uttar Pradesh) which is ancestral (husband side) and as per the will of my husband, it is under name of mine and my 2 sons. I also own a flat in Noida and 1 flat in Delhi. I have 2 daughters and 2 sons. Between my 2 sons, I would like to divide agricultural land in UP and also flat in Delhi. Between my daughters, I would like to divide the Noida flat equally. My queries are : 1) Can I write & register my will anywhere or do I need to get it done in UP. 2) I do not want to leave any gap such that my will is not challenged after my demise. Hence need to advise on the best way forward. 3) I also need legal advice on will drafting and registration