# Sibling seats for adding a second child to a stroller Which sibling seat can be added to a stroller so that a second child can ride along? Bugaboo Donkey 6 Sibling Seat: The sibling seat turns a Bugaboo Donkey 6 into a side\-by\-side double stroller for a second child\. Bugaboo Donkey 6 Sibling Seat certification: The Bugaboo Donkey 6 is certified to ASTM F833 \(latest version\), ASTM F2050 \(latest version\) and by the Juvenile Products Manufacturing Association \(JPMA\)\. Thule Sleek 2 Sibling Seat: Thule Sleek 2 Sibling Seat in Black converts a Thule Sleek 2 stroller into a sibling stroller\. Thule Sleek 2 Sibling Seat safety standard: Manual lists ASTM F833\-21\. Bugaboo Kangaroo Sibling Seat: It is made for the Bugaboo Kangaroo stroller and adds a second seat for tandem use\. Bugaboo Kangaroo Sibling Seat age and weight: The store recommends it from 6 months, with a maximum child weight of 40 lb \(18 kg\); it is not for newborns\. Cybex Gazelle S Seat Unit: The second seat converts the Gazelle S from a single to a double stroller so two children can ride at once\. Cybex Gazelle S Seat Unit fit: No additional adapters are needed to convert the stroller to a double\. ### 1. [Bugaboo Donkey 6 Sibling Seat](/products/ucp/albeebaby-com/9722090717415) (sold by albeebaby\.com) The sibling seat turns a Bugaboo Donkey 6 into a side\-by\-side double stroller for a second child\. - Safety standard: The Bugaboo Donkey 6 is certified to ASTM F833 \(latest version\), ASTM F2050 \(latest version\) and by the Juvenile Products Manufacturing Association \(JPMA\)\. (manual) - Age and weight: The store listing says the sibling seat is for children from 6 months up to 22 kg \(50 lbs\), while the Donkey 6 North American manual says the seat maximum is 23 kg \(50 lbs\); the sources disagree on the kilogram limit\. (listing) - Warranty: - - Dimensions: Sitting space at the widest point with the footrest is 19\.7 in long x 14\.5 in wide x 17\.3 in deep\. (listing) ### 2. [Thule Sleek 2 Sibling Seat](/products/ucp/albeebaby-com/9579254350055) (sold by albeebaby\.com) Thule Sleek 2 Sibling Seat in Black converts a Thule Sleek 2 stroller into a sibling stroller\. - Safety standard: Manual lists ASTM F833\-21\. (manual) - Age and weight: - - Warranty: - - Dimensions: Dimensions are 32\.7 x 17\.1 x 43\.5 inches\. (listing) ### 3. [Bugaboo Kangaroo Sibling Seat](/products/ucp/anbbaby-com/9471020040478) (sold by anbbaby\.com) It is made for the Bugaboo Kangaroo stroller and adds a second seat for tandem use\. - Safety standard: - - Age and weight: The store recommends it from 6 months, with a maximum child weight of 40 lb \(18 kg\); it is not for newborns\. (guide) - Warranty: The authorized retailer states that a full manufacturer warranty applies, but provides no duration or terms\. (guide) - Dimensions: The seat measures 17\.7 inches \(45 cm\) long by 11\.8 inches \(30 cm\) wide\. (guide) ### 4. [Cybex Gazelle S Seat Unit](/products/ucp/albeebaby-com/9564471230695) (sold by albeebaby\.com) The second seat converts the Gazelle S from a single to a double stroller so two children can ride at once\. - Safety standard: - - Age and weight: The US manual prints configuration limits of 35 lbs/15\.9 kg and 50 lbs/22\.7 kg; the global manual prints 15 kg and 22 kg, so the regional figures disagree\. (manual) - Warranty: Open\-box purchases include a 1\-year manufacturer's warranty and are final sale, not eligible for return or exchange\. (guide) - Dimensions: - ## Also cited in the text - Thule Sleek 2 Sibling Seat, What it is: Thule Sleek 2 Sibling Seat in Black converts a Thule Sleek 2 stroller into a sibling stroller\. (listing) - Bugaboo Kangaroo Sibling Seat, Purpose and compatibility: It is made for the Bugaboo Kangaroo stroller and adds a second seat for tandem use\. (guide) - Bugaboo Donkey 6 Sibling Seat, function: The sibling seat turns a Bugaboo Donkey 6 into a side\-by\-side double stroller for a second child\. (listing) - Cybex Gazelle S Seat Unit, conversion: The second seat converts the Gazelle S from a single to a double stroller so two children can ride at once\. (listing) - Cybex Gazelle S Seat Unit, adapters: No additional adapters are needed to convert the stroller to a double\. (listing) Every value in the table is a fact RoboTrunk checked, linked to the page it came from\. A dash means no checked fact fills that cell\. Prices and stock change, so this page prints neither: each product name links to its RoboTrunk page, which shows them live\. Written 2026-10-11T15:22:45.593Z. This page is published by RoboTrunk, a store built for shopping agents. 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