There is NO annual limit if the $161k was bestowed to the baby/kid via a nomination.
Contributions under the Retirement Sum Topping Up Scheme (RSTU) are
not counted toward the CPF Annual Limit ($37,740). The only RSTU limit is that, before age 55, you can't top up any more once the SA reaches the Full Retirement Sum ($166,000 in 2017).
You can top up anybody's CPF account -- anybody who is a citizen or permanent resident. (OK, babies aren't
born PRs. A PR application for a newborn takes time to be approved, if it's approved.) It's only the tax relief that is limited to certain relatives, and those certain relatives do not include children, grandchildren, nieces, and nephews (as examples).
Let's suppose a Singaporean baby is born in 2017. A generous grandmother wants to be generous. She can contribute $166,000 to the newborn's CPF Special Account, all in one go. She can also contribute $37,740 (CPF Annual Limit) to the newborn's CPF Medisave Account, for a total baby gift (to CPF) of $203,740 in 2017. That lucky baby also gets a $4,000 Medisave grant from the government, so the baby starts life with $207,740 in CPF. In 2018 that grandmother can contribute a little bit more to the baby's Medisave account, up to the Basic Healthcare Sum for 2018. Then she can contribute the balance of that year's $37,740 limit to the baby's Ordinary Account, if desired.
That'd be a nice way to start life, wouldn't it?