Re: Menu planning speicifically for guests
Start with planning what they will do the three weeks they are there. (i.e from landing in to flying back) I am assuming you will be suggesting them how to plan their day in terms of going out & since its family you might also already know what they are planning to do during their trip (shopping/sight seeing/meeting any friends)
Then figure out how many meals they will be eating at home including breakfast, snacks, lunch & dinner. THEN make a menu for every day keeping in mind their daily activities. So the days the meals they have at home you can make roti/chawal/pasta & for the meals they eat out, you can do rolls/sandwiches
Here is a sample menu (its from the days I was cooking for 2 days worth of food because of my back pain) 
Note you can always change the dishes around but at least start writing in this format.
Divide your menu for each weak so this way when you do your once a week grocery shopping you’ll know exactly what to get without buying extra stuff.
Figure out in advance with what meals you want to serve soda/pop so you buy enough for that week’s worth & not extra.
As for suggestions as Kinz said freeze Shami Kababs/Seekh Kababs or you can even freeze spring rolls/Qeema Samosas/puff pastries for snacks.
For breakfast go to Sams Club/Costco like stores if you can & buy bagels/croissants/eggs in bulk. If you have toaster, put it out & let your guests know from the first day that they have the options of toasting bread to their own liking & eating with desired spreads (let them know their options)
Also plan something where if one day you are doing heavy/mehnat wala breakfast then do next meal light such as vegetable/daal/kichri/veggie pulao. It will be less work for you & guests will appreciate the fact that you looked after their stomachs.
Since between breakfast & lunch there is not much time , plan your lunches keeping in mind your speed in a certain dish. Meals that might seem easy to us might seem time consuming to you, or meals that you find easy to make might seem time consuming to us. You know your self better so plan lunches accordingly.
Another thing you can do is depending on what you plan to cook the next day, you can prep for it the day before while cooking something else. For eg. if you are cooking something that requires sliced onions & the next day meal also consists of fried onions, slice in bulk & store it covered for the next day.
You can broil Tandoori chicken & serve with parathas/puriyan, salas, chutney & raita & then for the next meal shred the the same tandoori meat & make club sandwiches out of it.
Another very important thing to keep in mind is never ever worry about pleasing ever single palette. They are your family, you will be on your 36 weeks mark & they are on vacation where its more about having fun in general with family rather than worrying about eating favorite foods or being snobby about what one person prefers or what one person likes. I am saying this with experience.
I’ll add more later. GTG now.
