dont't get frustrated. Think of it in another perspective, why be bothered about what others may or may not buy. Some people doesnt even have relative so only the couple buying for their newborn. If they buy it is a PLUS. If they doesnt then just be neutral.
It is a big sacrifice to come over to monitor your maid already. Imagine your mother in law doesnt have anymore friends here for a month or two.
It is also usually a custom in Msia for grandparents to give NB jewellery or angpow after they are born or during full moon.