hello, I currently have a 3.5 week old daughter and we have never been able to get her to sleep in her bassinet. The only time she will sleep is when she is on either myself or my partner. For night times currently we have a "cosy sleeper" which goes in between my partner and I. She sleeps great in there. But I am worried on how safe these things are. We've used it for about 2 weeks now. But would like your opinion on it . It has 4 walls. Half of which are mesh. And we wrap her correctly when she is in it. Thankyou

Red Nose has information in general about things to consider when wanting to use specific products.
https://rednose.org.au/article/baby-safe-sleeping-products

The following information is also available about co-sleeping, whether using a specific “co-sleeping product” or not.
Sharing a sleep surface with a baby can increase the risk of SUDI. A considerable proportion of SUDI occur on a shared sleeping surface.
Babies most at risk of SUDI when sharing a sleep surface are those less than 3 months postnatal age, babies who were born preterm or small for gestational age.
The risks are always much greater if parents smoke or are under the influence of alcohol or drugs (prescription or illegal) that cause sedation and impair their ability to respond to their baby.
There is a very high risk of infant death, including deaths attributed to fatal sleeping accidents, when a baby shares a sofa or couch with an adult during sleep.
https://rednose.org.au/article/is-it-safe-to-sleep-with-my-baby

Red Nose recommends that the safest place for baby to sleep, is in a cot that meets standards & is in the parents/caregivers room.
Always place baby on their back for sleep, ensure baby’s head & face remain covered during sleep & that environment is smoke free.

There are a lot of portable sleep spaces on the market, which do not meet the Safe Sleep guidelines, mainly due to a number of safety concerns about pods & nests & on how they are used.
These include soft, padded sides & soft base & minimal height on sides.
Product Safety recommends sides of a bassinet should be 300mm high
https://www.productsafety.gov.au/products/babies-kids/kids-furniture/bassinettes
Some of them are designed specifically for co-sleeping, however the baby is still at risk of adult bedding being pulled up over the baby’s head & face.

A parent falling asleep with a baby prone (on the tummy) on the parent’s chest and unobserved can be problematic as prone positioning reduces baby’s arousal mechanisms that protect baby’s airway; baby’s nose may become obstructed by clothing, or parent’s body or breast; or an unobserved baby may become positioned with his/her chin to chest, which will also obstruct baby’s airway
You can download this information from this link - Sharing a sleep surface with a baby.
https://rednose.org.au/article/is-it-safe-to-sleep-with-my-baby

It is also recommended that babies who a sharing a sleep surface are not wrapped/swaddled.
Babies must not be wrapped if sharing a sleep surface (including bed-sharing).
https://rednose.org.au/article/wrapping-babies

There are many places where you can support for settling baby, including your local maternal child family health nurse.
if you let me know what State you are from I can send you some local links as well.