Without being known by anyone
Mizuko service might not be something we can talk about so openly. There must be people who have wish such as "would do it without telling to the family if possible”.
There is no problem if it is possible to put "Jizo" stature proudly, but you might have a feeling still, such as "don’t want to be known by family and friends", yet "would like to place object at familiar place and pray any time".
For such people, Mizuko service is possible by determining "memorial service object can be recognized by only you". You have better to set the object as worthy for Mizuko to come to see, such as pretty dolls.
The most important thing is that you'll never forget Mizuko forever.